Imaging Pearls ❯ Adrenal ❯ Incidental Adrenal Masses
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- OBJECTIVE. The purpose of our study was to evaluate the diagnostic utility of adrenal mass biopsy in patients without known or suspected extraadrenal primary malignancy.
CONCLUSION. Adrenal mass biopsy had low diagnostic yield, with low sensitivity and low specificity for malignancy. A biopsy result of adrenocortical neoplasm did not reliably differentiate benign and malignant adrenal masses.
CLINICAL IMPACT. Biopsy appears to have limited utility for the evaluation of incidental adrenal masses in patients without primary extraadrenal malignancy.
Adrenal Mass Biopsy in Patients Without Extraadrenal Primary Malignancy: A Multicenter Study
Satheesh Krishna et al.
AJR 2024; 222:e2329826 - Key Finding
- In patients without primary extraadrenal malignancy, adrenal mass biopsy had a diagnostic yield of 64% (44/69; 95% CI, 51–75%), concordance with the diagnosis from subsequent surgical resection of 100% (12/12), and sensitivity and specificity for detection of malignancy (by subsequent resection or imaging follow-up) of 73% (22/30) and 54% (21/39), respectively.
Importance
- Adrenal mass biopsy has limited diagnostic utility for theevaluation of incidental adrenal masses in patients without primary extraadrenal malignancy.
Adrenal Mass Biopsy in Patients Without Extraadrenal Primary Malignancy: A Multicenter Study
Satheesh Krishna et al.
AJR 2024; 222:e2329826 - “Incidental adrenal masses with macroscopic fat on imaging were historically considered to unequivocally represent myelolipomas. However, it has recently been recognized that adrenal adenomas can contain small amounts of macroscopic fat due to myelolipomatous degeneration and that ACC may also rarely contain small amounts of macroscopic fat. In the present study, among the 18 adrenal masses with macroscopic fat, only four were malignant; biopsy had a sensitivity of 50% for these malignancies.”
Adrenal Mass Biopsy in Patients Without Extraadrenal Primary Malignancy: A Multicenter Study
Satheesh Krishna et al.
AJR 2024; 222:e2329826 - “In conclusion, this study identified that biopsy of adrenal masses in patients without a known or suspected primary extraadrenal malignancy was safe, without any significant immediate postprocedural complications. When diagnostic, adrenal mass biopsy had high sensitivity and specificity for malignancy. However, adrenal mass biopsy had a high nondiagnostic rate, and, when classifying nondiagnostic biopsies as false results, had low sensitivity and specificity for malignancy. In particular, adrenal mass biopsies were commonly reported as adrenocortical neoplasm, a result that could not reliably differentiate benign and malignant adrenal masses.”
Adrenal Mass Biopsy in Patients Without Extraadrenal Primary Malignancy: A Multicenter Study
Satheesh Krishna et al.
AJR 2024; 222:e2329826
- “Ganglioneuroma is a rare benign tumor comprised of ganglion and Schwann cells and arises along the sympathetic chain, including the adrenal medulla in 20%–30% of cases. Most patients are asymptomatic young adults. On CT images, ganglioneuroma is homogeneously hypoattenuating (<40 HU) with mild progressive contrast enhancement. Stippled intralesional calcifications are common, occurring in roughly half of cases. Cystic change is uncommon.”
Adrenal Neoplasms: Lessons from Adrenal Multidisciplinary Tumor Boards
Ryan Chung et al.
RadioGraphics 2023; 43(7):e220191 July 2023 - •An adrenal nodule with homogeneous low attenuation (≤10 HU) on nonenhanced CT images and microscopic fat on chemical shift MR images is diagnostic of an adenoma
• Adrenal washout CT findings should not be stand-alone features for the diagnosis of lipid-poor adenoma; other features such as a mass size, heterogeneity, and clinical context should be considered to avoid misdiagnosis
• Adrenal washout CT is most useful for distinguishing adenoma from metastasis in patients with known nonhypervascular primary malignancy
Adrenal Neoplasms: Lessons from Adrenal Multidisciplinary Tumor Boards
Ryan Chung et al.
RadioGraphics 2023; 43(7):e220191 July 2023 - Adrenal Masses with Cystic and/or Necrotic Change
- Cyst
- Metastases
- Pheochromocytoma
- Adrenal cortical carcinoma - “Primary adrenal pleomorphic spindle cell sarcoma (PSCS) is an exceedingly rare mesenchymal tumour that was previously known as malignant fibrous histiocytoma. It commonly occurs in extremities, retroperitoneum, peritoneal cavity and rarely in visceral organs.”
Pleomorphic spindle cell sarcoma of the adrenal gland: an extremely rare cause of a large abdominal mass and a challenging diagnosis.
Omar Mohamed Ozaal AM, Rajendra S.
J Surg Case Rep. 2022 Mar 22;2022(3):rjac049
- “Adrenal cysts are subdivided into pseudocysts, endothelial (also called vascular) cysts, epithelial (also called mesothelial) cysts and parasitic cysts, a classification model that requires microscopic investigation of the resected specimen5. On routine histology, adrenal cysts are benign, fluid-containing lesions with a peripheral cyst wall; identification of the cell lining (or lack thereof) is the foundation for determining the correct cyst subtype. Careful sampling of the cyst wall is usually recommended in order to obtain sufficient material to correctly identify the cyst subtype and safely exclude clinically important differential diagnoses.”
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press) - “The most common subtype is the adrenal pseudocyst comprising up to 80% of all adrenal cysts in some series. These cysts are believed to arise from an encapsulated adrenal haemorrhage. The cyst contains a fluid with extravasated erythrocytes and various amounts of fibrin, and the surrounding capsule is a thick, fibrous structure that lacks an internal cell lining. Haemosiderin-containing macrophages might be present within the capsule. Several vascular channels can be detected in adrenal pseudocysts, which suggests a vascular origin similar to that of endothelial cysts.”
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press) - “Endothelial cysts are diagnosed when the capsule contains a monolayer of either endothelial or lympho-endothelial cells5. To safely identify these cell types, immunohistochemical analysis could be useful. Positive staining for the platelet endothelial cell adhesion molecule antigen CD31 and the transcription factor ERG are seen for endothelial cells, whereas CD31 and D2-40 (which recognizes podoplanin) staining highlight lympho-endothelial cells5,18. Epithelial cysts of the adrenal gland are usually uniloculated lesions, with a thin capsule lined by a flat to cuboidal cell layer positive for the transcription factor WT1 and a calcium-binding protein, calretinin.”
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press) - “Most patients with adrenal cysts are asymptomatic; however, 10% present with symptoms of mass effect such as abdominal pain or discomfort9. In a large series of adrenal cysts published in 2022, the median size at the time of initial diagnosis was 4.8 cm, ranging from 0.5 cm to 20 cm. In older studies, which included a higher proportion of patients who underwent surgery, the average cyst size was 4.7–9.6 cm Surprisingly, larger cysts (>5 cm) are more common in younger patients, with a median age of 37 years versus 51 years in patients with cysts <5 cm. The prevalence of symptoms of mass effect in patients with cysts >5 cm is 20%, which is tenfold higher than in patients with cysts <5 cm (2%)9. Bilateral adrenal cysts occur in 3–8% of patients and unilateral lesions show equal left and right distribution.””
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press) - “Cystic phaeochromocytomas are extremely rare, accounting for 3.2% of phaeochromocytomas and 0.27% of all adrenal tumours, with most evidence originating from case reports and small case series of up to 21 patients. Most patients are diagnosed in the sixth to seventh decade of life and mainly present with incidentalomas, whereas 24% are discovered based on symptoms of catecholamine excess. Notably, in the largest series of 21 patients, all had a biochemically active phaeochromocytoma, and even patients with an incidentally discovered phaeochromocytoma reported symptoms of catecholamine excess12. The cystic component in cystic phaeochromocytomas probably develops as a result of haemorrhagic degeneration.”
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press) - “Adrenal cysts are rare adrenal lesions that are mostly found incidentally. Although the subtyping of adrenal cysts can have limited clinical relevance, care must be taken not to miss a malignant neoplasm with a cystic phenotype. Hormonal screening is recommended to exclude hormonal overproduction by cysts. Parasitic adrenal cysts require exposure to E. granulosus, which is endemic in certain parts of the world. The management of a benign adrenal cyst is typically conservative. As most physicians are unfamiliar with adrenal cysts, the management of a newly discovered adrenal cyst should preferably be discussed at an adrenal multidisciplinary team meeting.”
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press) - “In the absence of symptoms or functionality, the best management strategy for adrenal cysts is not clear. When a cyst is accidentally discovered and with clearcut benign imaging characteristics, whether the patient should undergo follow-up imaging for detection of growth is also not clear. In addition, the ideal frequency and length of followup for such imaging are unknown. Most benign adrenal cysts are asymptomatic, but they may grow and give rise to symptoms of mass effect. The predictors of growth or potential haemorrhage are unclear and thus monitoring should be individualized. The pathogenic drivers behind the development of adrenal cysts and growth are also incompletely understood.”
Adrenal cysts: an emerging condition
Jan Calissendorff et al.
Nature Reviews Endocrinology 2023 (in press)
- “Adrenal lesions are common incidental findings identified on imaging studies not performed for suspected adrenal disease. A size cutoff of 1 cm or larger has typically been used to recommend further diagnostic evaluation in the absence of concerning clinical features. More than 75% of adrenal incidentalomas are benign adenomas and are nonfunctional; however, evaluation for hormone excess and potential malignancy are of critical importance, as these typically require surgical excision.”
American Association of Endocrine Surgeons Guidelines for Adrenalectomy: Executive Summary
Linwah Yip, et al.
JAMA Surg. doi:10.1001/jamasurg.2022.3544 Published online August 17, 2022. - “Adrenal adenomas often contain high lipid content, which can be detected by both computed tomography (CT) and magnetic resonance imaging (MRI). Tumor density of less than 10 Hounsfield units (HU) on noncontrast CT represents a lipid rich adenoma.4 An adrenal protocol CT refers to unenhanced images followed by administration of intravenous contrast and repeated imaging at 60 to 75 seconds (venous phase) at 15 minutes (delayed phase).Benign adenomas typically exhibit rapid contrast washout, defined as an absolute percentage washout greater than 60% or relative percentage washout greater than 40% at 15 minutes’ delay.”
American Association of Endocrine Surgeons Guidelines for Adrenalectomy: Executive Summary
Linwah Yip, et al.
JAMA Surg. doi:10.1001/jamasurg.2022.3544 Published online August 17, 2022. - “The prevalence of adrenocortical carcinoma (ACC) in incidentally discoveredadrenal nodules is less than0.5%for nodules smaller than 4 cm, 5% for nodules from 4 to 6 cm, and up to 35% for nodules larger than 6 cm at presentation. Metastatic disease to the adrenal gland can be identified in 1% to 3% in patients without a history of malignancy and up to 8% in patients with a history of extra-adrenal malignancy. Other features in addition to size should be considered when assessing risk of either a primary or secondary malignancy in an adrenal incidentaloma”
American Association of Endocrine Surgeons Guidelines for Adrenalectomy: Executive Summary
Linwah Yip, et al.
JAMA Surg. doi:10.1001/jamasurg.2022.3544 Published online August 17, 2022.
- “The 2017 American College of Radiology White Paper was the most used guideline, yet the management of indeterminate adrenal incidentalomas was highly variable with no single management option reaching a majority. Hormonal evaluation and endocrinology consultation was most often rarely or never recommended. The results of the survey indicate wide variability in the interpretation of imaging findings and management recommendations for incidental adrenal nodules among surveyed radiologists. Further standardization of adrenal incidentaloma guidelines and education of radiologists is needed.”
Management of incidental adrenal nodules: a survey of abdominal radiologists conducted by the Society of Abdominal Radiology Disease‐Focused Panel on Adrenal Neoplasms
Michael T. Corwin et al.
Abdominal Radiology (2022) 47:1360–1368 
Management of incidental adrenal nodules: a survey of abdominal radiologists conducted by the Society of Abdominal Radiology Disease‐Focused Panel on Adrenal Neoplasms
Michael T. Corwin et al.
Abdominal Radiology (2022) 47:1360–1368- “The majority of respondents either rarely or never rec- ommend hormonal evaluation or endocrinology consultation when describing an adrenal incidentaloma. Both the American Association of Clinical Endocrinologists and the European Society of Endocrinology recommend hormonal evaluation to determine the functional activity in all patients with adrenal incidentalomas. The 2017 ACR white paper advises consideration for biochemical evaluation for most incidentalomas as adrenal hyperfunction may not be clinically evident."
Management of incidental adrenal nodules: a survey of abdominal radiologists conducted by the Society of Abdominal Radiology Disease‐Focused Panel on Adrenal Neoplasms
Michael T. Corwin et al.
Abdominal Radiology (2022) 47:1360–1368
- "Adrenal hemangiomas (AH) are extremely rare tumors of vascular origin. Around 70 surgical cases have been pre- sented, and overall they represent nearly 0.01% of all adrenal tumors. AHs are mostly clinically silent and are detected as incidentalomas on cross-sectional imaging studies, which are performed for unrelated reasons. There is a female predominance of 2:1 and are mostly located unilaterally. They are characteristically detected in the sixth or seventh decades of life, and their size may range from 2 cm to 25 cm in diameter. They are mostly hormonally inactive, but rare hormone-secreting AHs have been reported.”
Cross‐sectional imaging features of unusual adrenal lesions: a radiopathological correlation
Karaosmanoglu AD et al.
Abdominal Radiology (2021) 46:3974–3994 - "Wolman disease (WD) is a disease characterized by a severe deficiency of the lysosomal acid lipase enzyme with subsequent lipid deposition in multiple organs. Triglycerides, cholesterol esters, and low-density lipoproteins cannot be hydrolyzed within the cells due to the absence of this enzyme. It is inherited in an autosomal recessive fashion and is mostly fatal within the first year of life. It is a very rare disease with around less than 100 cases have been reported so far, to the best of our knowledge. Adrenal glands, reticuloendothelial system, and enteric mucosa are mostly affected.”
Cross‐sectional imaging features of unusual adrenal lesions: a radiopathological correlation
Karaosmanoglu AD et al.
Abdominal Radiology (2021) 46:3974–3994
- "Wolman disease (WD) is a disease characterized by a severe deficiency of the lysosomal acid lipase enzyme with subsequent lipid deposition in multiple organs. Triglycerides, cholesterol esters, and low-density lipoproteins cannot be hydrolyzed within the cells due to the absence of this enzyme. It is inherited in an autosomal recessive fashion and is mostly fatal within the first year of life. It is a very rare disease with around less than 100 cases have been reported so far, to the best of our knowledge. Adrenal glands, reticuloendothelial system, and enteric mucosa are mostly affected.”
Cross‐sectional imaging features of unusual adrenal lesions: a radiopathological correlation
Ali Devrim Karaosmanoglu et al.
Abdominal Radiology (2021) 46:3974–3994 - "The detection rates of adrenal masses are increasing with the common and widespread use of cross-sectional imaging. Adre- nal adenomas, myelolipomas, metastases, pheochromocytomas, and adrenocortical tumors are well-known and relatively common adrenal tumors. However, there are many less-known neoplastic and nonneoplastic adrenal diseases that might affect the adrenal glands in addition to these common lesions. These rare entities include, but are not limited to, hydatid cysts, congenital adrenal hyperplasia, Wolman disease, adrenal tuberculosis, primary adrenal lymphoma. This article aims to present imaging findings of these unusual lesions in accordance with their pathologic characteristics. We think that the simultaneous presentation of the pathological findings with the imaging features may facilitate the learning process and may potentially enhance the recognition of these entities.”
Cross‐sectional imaging features of unusual adrenal lesions: a radiopathological correlation
Ali Devrim Karaosmanoglu et al.
Abdominal Radiology (2021) 46:3974–3994 - “In conclusion, a lesion LD ≥ 10 mm seems to be a reasonable cutoff for determining adrenal abnormality. In the current cohort, none of patients with the subcentimeter adrenal lesion that had very low, low, or equivocal likelihood of being a focal adrenal lesion had either of pheochomocytoma or malignant tumors at all although 5–6% of them had clinically significant adrenal lesions. In addition, higher cutoffs significantly decreased sensitivity.”
Clinical significance of a 10‐mm cutoff size for adrenal lesions: a retrospective study with 547 non‐oncologic patients undergoing adrenal computed tomography
Myoung Kyoung Kim et al.
Abdominal Radiology (2022) 47:1091–1097
- “Adrenal incidentalomas are defined as nodules greater than 1 cm incidentally discovered during imaging performed for nonadrenal disorders. Adrenal nodules are common, occurring in 4.4% of patients undergoing computed tomography (CT), and in 6% of the population in a large autopsy series. Because the prevalence of adrenal nodules increases with age, and as cross-sectional imaging use continues to expand, the overall number of incidental adrenal nodules detected is expected to increase.”
Incidental Adrenal Nodules
Daniel I. Glazer, Michael T. Corwin, William W. Mayo-Smith
Radiol Clin N Am 59 (2021) 591–601 - "Most incidentally detected adrenal nodules are benign, most commonly nonfunctioning adenomas. Although almost all small adrenal nodules can safely be ignored, a small percent- age of incidentally discovered adrenal nodules require further work-up to determine if they represent clinically relevant neoplasms (adrenocortical carcinoma [ACC], metastases, or pheo- chromocytoma).”
Incidental Adrenal Nodules
Daniel I. Glazer, Michael T. Corwin, William W. Mayo-Smith
Radiol Clin N Am 59 (2021) 591–601 - “When an adrenal nodule volume is encountered that is primarily soft tissue density but with small focal areas of macroscopic fat, adenoma should be in the differential diag- nosis. Although myelolipomas and adenomas are benign, the distinction is important because myelolipomas are not hyperfunctioning, whereas adenomas may be. Macroscopic fat has also been rarely reported in ACC; however, the tumors were large (>6 cm) and contained small proportions of fat.”
Incidental Adrenal Nodules
Daniel I. Glazer, Michael T. Corwin, William W. Mayo-Smith
Radiol Clin N Am 59 (2021) 591–601 - ‘If the absolute washout is greater than or equal to 60% ([enhanced HU – delayed HU]/[enhanced HU – nonenhanced HU]), then a diagnosis of lipid-poor adenoma is made. It should be noted that approximately one-third of pheochromocytomas can washout greater than or equal to 60%, and therefore should remain in the differential diagnosis if there is biochemical evidence of pheochromocytoma. It is also important to note that hypervascular metastases, including HCC and RCC, can washout greater than 60%.”
Incidental Adrenal Nodules
Daniel I. Glazer, Michael T. Corwin, William W. Mayo-Smith
Radiol Clin N Am 59 (2021) 591–601 - ‘Generally, an adrenal protocol CT consists of a nonenhanced acquisition through the abdomen using reduced radiation dose techniques, followed by radiologist review. If the adrenal nodule measures less than or equal to 10 HU, no further imaging is necessary because the nodule is diagnostic of a lipid-rich adenoma. If the nodule measures greater than 10 HU, then IV contrast is adminis- tered, and images are obtained at 60 to 70 seconds and at 15 minutes following injection. This allows for the absolute washout calculation described previously. If the nodule being evaluated has sus- picious morphologic features (central low density, irregular margins) or greater than 4 cm, performing a washout CT may not be necessary because surgical consultation is recommended.”
Incidental Adrenal Nodules
Daniel I. Glazer, Michael T. Corwin, William W. Mayo-Smith
Radiol Clin N Am 59 (2021) 591–601
- The Incidental Cystic Adrenal Mass: Differential Dx
- Adrenal cyst
- Adrenal hemorrhage (old)
- Adrenal pheochromocytoma
- Primary adrenal carcinoma
- Adrenal metastases (melanoma, renal cell carcinoma) - The Incidental Cystic Adrenal Mass: Differential Dx
- Adrenal cyst
- Adrenal hemorrhage (old)
- Adrenal adenoma
- Adrenal pheochromocytoma
- Primary adrenal carcinoma
- Adrenal metastases (melanoma, renal cell carcinoma)
- Uncommon benign tumors (i.e. ganglioneuroma, unusual myelolipoma) - The Incidental Cystic Adrenal Mass: Imaging Parameters
- Lesion size
- Lesion shape (round, oval or irregular shape)
- Enhancement if any (especially peripheral)
- Presence of calcification (peripheral or central)
- Unilateral vs bilateral adrenal involvement
- Extra-adrenal findings
- Clinical history and presentation (i.e. hypertension, anti-coagulation therapy)
- “Adrenal collision tumor is a rare tumor defined as the coexistence of two or more adjacent but histologically distinct neoplasms in the adrenal gland without a histological admixture at the interface.”
A collision between vascular adrenal cyst and adrenocortical adenoma
Hiroko Tagawa et al.
Radiology Case Reports 16 (2021) 1294–1299
- Large Adrenal Masses (4 cm or greater)
Benign
- Adrenal Adenoma
- Adrenal Cyst
- Adrenal Myelolipoma
- Adrenal Hemorrhage
- Pheochromocytoma
- Ganglioneuroma - Large Adrenal Masses (4 cm or greater)
Malignant
- Primary adrenal carcinoma
- Adrenal metastases
- Adrenal lymphoma
- Pheochromocytoma (malignant 10%)
- Adrenal sarcoma (rare) - Large Adrenal Masses (5cm or greater)
Adrenal mass analysis
- Unilateral vs bilateral
- Pattern of enhancement
- Presence of calcification
- Extra adrenal findings - “The prevalence of malignancy in patients with adrenal tumors of 4 cm or more in diameter was 31%. Older age, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were associated with an increased risk for malignancy. Clinical context should guide management in patients with adrenal tumors of 4 cm or more in diameter.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39. - “Of 4085 patients with adrenal tumors, 705 (17%) had adrenal masses measuring 4 cm or more in diameter; of these, 373 (53%) were women, with a median age of 59 years (range, 18-91 years) and median tumor size of 5.2 cm (range, 4.0-24.4 cm). Underlying diagnoses were adrenocortical adenomas (n=216 [31%]), pheochromocytomas (n=158 [22%]), other benign adrenal tumors (n=116 [16%]), adrenocortical carcinomas (n=88 [13%]), and other malignant tumors (n=127 [18%]).”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39. - "Compared with benign tumors, malignant tumors were less frequently diagnosed incidentally (45.5% vs 86.7%), were larger (7 cm [range, 4-24.4 cm] vs 5 cm [range, 4-20 cm]), and had higher unenhanced computed tomographic (CT) attenuation (34.5 Hounsfield units [HU] [range, 14.1-75.5 HU] vs 11.5 HU [range, −110 to 71.3 HU]; P<.001). On multivariate analysis, older age at diagnosis, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were all found to be statistically significant predictors of malignancy.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39. 
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39.- "We found that patients with adrenal tumors of at least 4 cm in diameter represent a heterogeneous group with an overall malignancy rate of 31%. We found that older age at the time of discovery of an adrenal mass, male sex, nonincidental mode of discovery, larger tumor size, and indeterminate imaging characteristics are predictors of a malignant adrenal mass. However, there are important differences in presentation and risk factors for ACC vs other malignant tumors, most notably sex (64% vs 35% women), age at diagnosis (median of 50 vs 66 years), and the presence of bilateral adrenal tumors (0% vs 30%).”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39. - “Pheochromocytomas were diagnosed in 22% of our cohort patients, with approximately half being discovered incidentally (54%). Thus, it is essential to biochemically exclude PHEO, especially in an adrenal mass with indeterminate imaging characteristics. The prevalence of PHEO in patients with incidentally discovered adrenal tumors of any size was previously reported to be 4.2%.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39. - “It is important to note that in a third of the patients with malignant adrenal tumors, the diagnostic evaluation and management differed on the basis of etiology. We recommend that the management of patients with large adrenal tumors should be individualized to the patient's circumstances and presentation, taking into account patient age, sex, mode of discovery, imaging phenotype including unenhanced CT tumor attenuation, rate of tumor growth and size, hormonal activity, and comorbidities. An active or previously diagnosed extraadrenal malignancy should raise the suspicion for metastases.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39. - "Large adrenal tumors are most frequently diagnosed incidentally and encompass a heterogeneous group. Tumor size alone is not a reliable determinant of malignancy. The overall prevalence of malignancy in patients with adrenal tumors of at least 4 cm in diameter was 31%. Risk of malignancy was associated with age at diagnosis, male sex, nonincidental mode of discovery, larger tumor size, and indeterminate imaging characteristics. All ACCs, PHEOs, and malignant adrenal tumors other than ACC demonstrated unenhanced CT attenuation of more than 10 HU, which supports the concept that malignancy and PHEO can be excluded with certainty in patients with adrenal tumors with unenhanced CT attenuation of less than 10 HU.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39.
- Bilateral Adrenal Masses: Differential Dx
- Adenoma
- Pheochromocytoma
- Metastases
- Hematoma
- Infection (TB)
- “Ganglioneuroma is a benign tumor arising from the sympathetic nerves or within the adrenals. This lesion is more frequently detected in the mediastinum or retro- peritoneum than in the adrenal medulla. Usually, it is a small round mass (2–3cm) with well-defined smooth margins and an inhomogeneous appearance due to mixoid components.”
Imaging features of adrenal masses
Domenico Albano et al.
Insights into Imaging (2019) 10:1 - "On CT, it appears as a well-circumscribed solid iso- or hypoattenuating lesion, which may display calcifications, necrosis, and hemorrhagic areas. It remains hypoattenuating on early post-contrastographic phases, while becoming hyperattenuating on delayed phases due to persistent enhancement.”
Imaging features of adrenal masses
Domenico Albano et al.
Insights into Imaging (2019) 10:1 - “Ganglioneuromas are rare, benign neurogenic tumors that arise from sympathetic ganglia. The tumors are composed of mature Schwann cells, ganglion cells, and nerve fibers. Ganglioneuromas may arise anywhere along the paravertebral sympathetic plexus and occasionally from the adrenal medulla. The retroperitoneum (32%–52% of cases) and posterior mediastinum (39%– 43%) are the two most common locations for a ganglioneuroma, followed by the cervical region (8%– 9%).”
Neurogenic Tumors in the Abdomen: Tumor Types and Imaging Characteristics
Sung Eun Rha et al.
RadioGraphics2003;23:29–43 - “Adrenal ganglioneuromas do not typically secrete exogenous hormones; thus, systemic manifestation of disease would not be expected. The tumor is commonly identified serendipitously in patients undergoing radiologic study for other reasons. This occult nature often presents a challenge to the radiologist attempting to differentiate adrenal ganglioneuroma from other nonhyperfunctioning adrenal tumors such as adenoma, adrenocortical carcinoma, myelolipoma, and hemangioma.”
Primary adrenal ganglioneuroma: CT findings in four patients.
G L Johnson, R H Hruban, F F Marshall ,E K Fishman
American Journal of Roentgenology. 1997;169: 169-171. - Adrenal Ganglioneuroma: Facts
- Benign tumor arising from neural crest tissue
- Arise in the adrenal medulla but do not secrete any specific hormone
- Usually detected as an incidental lesion - Adrenal Ganglioneuroma: CT Findings
- 5-9 cm in size
- Usually smooth and homogeneous type masses
- May contain calcification
- Is not locally invasive - “Adrenal ganglioneuroma is an uncommon benign tumor that is a solid adrenal mass on CT.The specific diagnosis requires either biopsy or surgical removal for documentation.”
Primary Adrenal Ganglioneuroma: CT Findings in Four Patients
Johnson GL et al.
AJR 1997;169:169-171 - "Calculations of washout are based on densitometry measurements on delayed postcontrast images relative to the enhancement at portal venous imaging (portal venous phase minus nonenhanced imaging) for absolute washout or portal venous phase attenuation alone for relative washout cal- culations. An absolute washout value greater than or equal to 60% or a relative washout value greater than or equal to 40% is used to identify adrenal adenomas.”
Technical and Interpretive Pitfalls in Adrenal Imaging
Nandra G et al.
RadioGraphics 2020; 40:1041–1060 - “Hypervascular metastases, such as those from renal cell carcinoma and hepatocellular carci- noma, are known to demonstrate washout that can satisfy criteria for an adenoma.Therefore, care must be taken in patients with a known primary hypervascular tumor, with consideration of further imaging such as FDG PET/CT, close follow-up, or tissue confirmation.”
Technical and Interpretive Pitfalls in Adrenal Imaging
Nandra G et al.
RadioGraphics 2020; 40:1041–1060 - “It may be challenging to differentiate hemor- rhage from other incidentally identified adrenal pathologic conditions. In such cases, assessment of temporal change and evaluation of the peri- adrenal fat is of use. Periadrenal infiltration or haziness may be visualized from the extension of hematoma into the surrounding tissues.Temporal resolution with a reduction in attenuation is commonly depicted with adrenal hemorrhage at follow-up imaging. Calcification and pseudocyst formation can also occur in the longer term.”
Technical and Interpretive Pitfalls in Adrenal Imaging
Nandra G et al.
RadioGraphics 2020; 40:1041–1060 - “Adrenal calcification is commonly observed in benign pathologic conditions, typically the sequelae of prior infection or hemorrhage. Calcification is also rarely appreciated in benign adrenal lesions, including cysts, adenomas, and myelolipomas. The presence of calcification does not invariably determine a benign cause, as adrenal calcification may also be identified in malignant pheochromocytomas and in up to 30% of adrenocortical carcinomas.The morphology of calcification within adrenocortical carcinoma is variable, with punctate, patchy, or nodular calcification.”
Technical and Interpretive Pitfalls in Adrenal Imaging
Nandra G et al.
RadioGraphics 2020; 40:1041–1060 - "The minority of endogenous Cushing syndrome cases are secondary to a primary adrenal cause (20%), with functioning adenomas and less commonly carcinomas being the major diagnos- tic considerations.There may be radiologic signs of a cortisol-secreting tumor, for example contralateral adrenal gland atrophy as a conse- quence of reduced pituitary ACTH secretion.”
Technical and Interpretive Pitfalls in Adrenal Imaging
Nandra G et al.
RadioGraphics 2020; 40:1041–1060 - “Primary hyperaldosteronism, due to either aldosterone-producing adenomas (APAs) or bilateral adrenal hyperplasia (BAH), is the most common cause of secondary hypertension. Careful radio- logic evaluation is required to differentiate the two, as a solitary-functioning adenoma is usually treated surgically while bilateral hyperplasia is typically treated medically.The identifica- tion of a nodule must be considered in the con- text of the remainder of the gland morphology, as the removal of a nodule that is actually part of a diffuse hyperplastic process may be futile . Similarly, the presence of numerous nodules can make the distinction between nodular hyperplasia and adenoma difficult.”
Technical and Interpretive Pitfalls in Adrenal Imaging
Nandra G et al.
RadioGraphics 2020; 40:1041–1060
- “Incidental adrenal nodules are quite common, occurring in 6% of the population in a large autopsy series and approximately 4% of all abdominal CT exams. The prevalence of incidental adrenal nodules increases with patient age, ranging from < 1% in patients in their 20’s to 7% in patients older than 70. Despite adrenal nodules being a very common finding, the vast majority of all incidentally detected adrenal nodules are benign.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - The most likely danger is that “[w]e’ll do what computers tell us to do, because we’re awestruck by them and trust them to make important decisions”. Radiologists can avoid this by educating themselves and future colleagues about AI, collaborating with researchers to ensure it is deployed in a useful, safe, and meaningful way, and ensuring that its use is always directed primarily towards the patient benefit. In this way, AI can enhance radiology, and allow radiologists to continually improve their relevance and value.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - ”Despite adrenal nodules being a very common finding, the vast majority of all incidentally detected adrenal nodules are benign [5]. The challenge is determining which incidentally detected nodules can safely be left alone (nonhyperfunctioning mass, myelolipoma, hemorrhage, cyst) and which require further work-up to be certain that they are not clinically significant neoplasms [adrenocortical carcinoma (ACC), pheochromocytoma, or metastases.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - “When an incidental adrenal mass is discovered at imaging, three important items to determine are a history of malignancy, presence of prior abdominal imaging, and symptoms of a hyperfunctioning mass, as this will guide subsequent management. First, if the patient has a history of malignancy, then an incidental mass has a higher chance of being a metastasis although the risk is still only 26–36%. Second, if prior imaging is available, greater than 1 year of stability is indicative of benignity. Third, if the patient presents with signs or symptoms of adrenal hyperfunction (including hypertension or Cushing’s features) this is suggestive of a biochemically active neoplasm that would require further investigation.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 
- ”Adrenal protocol CT is the modality of choice for evaluating adrenal masses as it can characterize a nodule using both density measurements and contrast washout. An adrenal protocol CT consists of a dose reduced unenhanced CT followed by measurement of the attenuation of the nodule in question. If the attenuation of the adrenal mass is ≤ 10 HU (Hounsfield Units), then no further imaging is necessary. If attenuation is > 10 HU, then intravenous contrast is administered, and the patient imaged at 70 s and 15 min to calculate contrast washout. Attenuation based diagnosis of adrenal nodules relies on the presence of lipid within an adenoma which reduces mean attenuation within the entire nodule.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - “Using a threshold of 10 HU on unenhanced images, a diagnosis of benign lipid-rich adenoma can be made with 98% specificity. However, lipid-poor benign adrenal nodules (approximately 20% of adenomas) measure greater than 10 HU on unenhanced CT but can be confidently diagnosed using contrast washout . Masses that have an absolute washout of ≥ 60% [(enhanced HU—delayed HU)/(enhanced HU—unenhanced HU)] or relative washout of ≥ 40% [(enhanced HU—delayed HU)/enhanced HU] are lipid- poor adenomas. Masses that have absolute washout of < 60% or relative washout of < 40% remain indeterminant and require further work-up.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - “Chemical shift MRI has been shown to have a sensitivity of 67% and specificity of 89–100%, similar to CT. However, subgroup analysis shows that chemical shift MRI is inferior to CT at diagnosing adenomas when a nodule measures > 20 HU at unenhanced CT. For this reason, adrenal protocol CT is favored over MRI unless there are patient specific factors which render CT undesirable such as history of iodinated contrast allergy.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - “In addition to imaging tests which are useful in determining if a mass is benign or malignant, biochemical screening is necessary to determine if a mass is hyperfunctioning. Recommendations regarding biochemical screening are somewhat varied, but both the ACR and the American Association of Clinical Endocrinologists and the American Association of Endocrine Surgeons recommend biochemical screening of most if not all patients presenting with an incidentally discovered adrenal mass.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2 - Adrenal Imaging Pitfalls
First, a subset of pheochromocytomas may demonstrate greater than 60% washout on adrenal protocol CT and could potentially be misdiagnosed as lipid-poor adenomas. It is for this reason that bio- chemical evaluation is recommended by the American Association of Clinical Endocrinologists and the American Asso- ciation of Endocrine Surgeons even for masses with benign imaging features. - Adrenal Imaging Pitfalls
Finally, both benign and malignant adrenal lesions may show uptake at FDG- 18 PET/CT. Although most benign conditions that can mimic adrenal malignancy are typically bilateral (adrenal hyperplasia, tuberculosis), it is possible for adenomas to demonstrate mild FDG avidity although it is typically less than liver. - “Even though almost all incidental adrenal nodules are benign, there is significant overlap of imaging features between malignant and benign entities at single phase contrast enhanced CT. No imaging features on single phase enhanced CT are reliably predictive of benignity although irregular margins and thick enhancing rim are very specific for malignancy. For this reason, in masses without definitely benign features on CT or MRI (attenuation ≤ 10 HU, macroscopic fat, signal loss on chemical shift MRI), further work-up with adrenal protocol CT is recommended in the absence of prior studies for comparison. Adrenal CT is favored over MRI as it can reliable distinguish between lipid-rich and lipid-poor adenomas versus other adrenal pathologies.”
Management of incidental adrenal masses: an update
Daniel I. Glazer, William W. Mayo‐Smith
Abdominal Radiology (in press 2019) https://doi.org/10.1007/s00261-019-02149-2
- Adrenal Masses Over 4cm
- Adrenal adenoma
- Pheochromocytoma
- Other benign tumors (cyst, myelolipoma)
- Primary Adrenal carcinoma
- Metastases (melanoma, hepatoma) - OBJECTIVE: To characterize large adrenal tumors (≥4 cm in diameter) and to identify features associated with malignancy.
CONCLUSION: The prevalence of malignancy in patients with adrenal tumors of 4 cm or more in diameter was 31%. Older age, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were associated with an increased risk for malignancy. Clinical context should guide management in patients with adrenal tumors of 4 cm or more in diameter.
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors.
Iñiguez-Ariza NM et al.
Mayo Clin Proc Innov Qual Outcomes. 2017 Dec 21;2(1):30-39. - “We suggest that clinical context, hormonal assessment, and image phenotype can together determine the need for adrenalectomy in patients with adrenal tumors of at least 4 cm in diameter. Patients with large adrenal tumors should be managed by an expert multidisciplinary team that includes endocrinologists, radiologists, and adrenal surgeons.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors.
Iñiguez-Ariza NM et al.
Mayo Clin Proc Innov Qual Outcomes. 2017 Dec 21;2(1):30-39. - “Of 4085 patients with adrenal tumors, 705 (17%) had adrenal masses measuring 4 cm or more in diameter; of these, 373 (53%) were women, with a median age of 59 years (range, 18-91 years) and median tumor size of 5.2 cm (range, 4.0-24.4 cm). Underlying diagnoses were adrenocortical adenomas (n=216 [31%]), pheochromocytomas (n=158 [22%]), other benign adrenal tumors (n=116 [16%]), adrenocortical carcinomas (n=88 [13%]), and other malignant tumors (n=127 [18%]).”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors.
Iñiguez-Ariza NM et al.
Mayo Clin Proc Innov Qual Outcomes. 2017 Dec 21;2(1):30-39. - “Compared with benign tumors, malignant tumors were less frequently diagnosed incidentally (45.5% vs 86.7%), were larger (7 cm [range, 4-24.4 cm] vs 5 cm [range, 4-20 cm]), and had higher unenhanced computed tomographic (CT) attenuation (34.5 Hounsfield units [HU] [range, 14.1-75.5 HU] vs 11.5 HU [range, -110 to 71.3 HU]; P<.001).”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors.
Iñiguez-Ariza NM et al.
Mayo Clin Proc Innov Qual Outcomes. 2017 Dec 21;2(1):30-39. - “On multivariate analysis, older age at diagnosis, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were all found to be statistically significant predictors of malignancy.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors.
Iñiguez-Ariza NM et al.
Mayo Clin Proc Innov Qual Outcomes. 2017 Dec 21;2(1):30-39. - PURPOSE: Large adrenal masses pose a diagnostic dilemma. The purpose of this study was twofold: first, to assess the degree of interobserver agreement in evaluating the morphology of pathologically proven adrenal adenomas and adrenocortical carcinomas larger than 4 cm in diameter; and second, to identify morphologic characteristics that correlated with the pathologic diagnosis.
CONCLUSION: Our study suggests that CT has the ability to consistently identify characteristics significantly correlated with benign vs. malignant adrenal tumors.
Interobserver agreement in distinguishing large adrenal adenomas and adrenocortical carcinomas on computed tomography.
Thomas AJ et al.
Abdom Radiol (NY). 2018 Nov;43(11):3101-3108. - “CT characteristics correlated with benignity included round shape (p = 0.02), an overall radiologic impression of a benign lesion (p < 0.0001), the presence of fat (p = 0.01), and a precontrast attenuation of less than 10 Hounsfield units (p < 0.0001). The latter two of these characteristics were highly specific for benign pathology (93% and 100%, respectively).”
Interobserver agreement in distinguishing large adrenal adenomas and adrenocortical carcinomas on computed tomography.
Thomas AJ et al.
Abdom Radiol (NY). 2018 Nov;43(11):3101-3108. 
- Bilateral adrenal lesions with adrenal insufficiency
- Metastatic lung cancer
- Pheochromocytoma
- TB
- Amyloidosis
- Lymphoma
- OBJECTIVE. The purpose of this study is to determine the differences in growth rate of adrenal adenomas and malignant adrenal nodules. RESULTS. A growth rate of 3 mm/year distinguished adenomas from malignant nodules with a sensitivity of 100% (95% CI, 86.8–100%) and a specificity of 100% (95% CI, 96.6–100%).
CONCLUSION. Approximately one-third of radiologically proven adrenal adenomas grew, all of which grew at a rate less than 3 mm/year. All malignant adrenal nodules grew, and all at a rate greater than 5 mm/year.
Differences in Growth Rate on CT of Adrenal Adenomas and Malignant Adrenal Nodules
Corwin MT et al.
AJR 2019; 213:1–5 - “Growth or stability over time are important factors in distinguishing benign from malignant adrenal nodules with indeterminate imaging features. However, a spe- cific growth rate to reliably distinguish between the two has not been established, to our knowledge. This is because benign nodules can grow. The results of our study show that approximately one-third of radiologically proven adrenal adenomas grow over time, and all adenomas that grew did so at a rate less than 3 mm/year, whereas all malignant adrenal nodules grew faster than 5 mm/year.”
Differences in Growth Rate on CT of Adrenal Adenomas and Malignant Adrenal Nodules
Corwin MT et al.
AJR 2019; 213:1–5 - ”In conclusion, approximately one-third of radiologically proven adrenal adenomas in our retrospective single-institution study grew over time, at a rate of 3 mm/year or less, whereas malignant adrenal nodules grew at a faster rate, greater than 5 mm/year. If confirmed by larger multiinstitutional studies, a growth rate of 3 mm/year may be a useful threshold to distinguish benign from malignant adrenal nodules.”
Differences in Growth Rate on CT of Adrenal Adenomas and Malignant Adrenal Nodules
Corwin MT et al.
AJR 2019; 213:1–5
- "Adrenalectomy is the standard of care for management of many adrenal tumor types and, in the United States alone, approximately 6000 adrenal surgeries are performed annually. Two general approaches to adrenalectomy have been described; (1) the open approach, in which a diseased adrenal is removed through a large (10-20 cm) abdominal wall incision, and (2) the minimally invasive approach, in which laparoscopy is used to excise the gland through incisions generally no longer than 1-2 cm. Given these disparate technique options, clear preoperative characterization of those specific disease features that inform selection of adrenalectomy approach is critically important to the surgeon.”
What the radiologist needs to know: the role of preoperative computed tomography in selection of operative approach for adrenalectomy and review of operative techniques. Rowe SP1, Lugo-Fagundo C1, Ahn H1, Fishman EK1, Prescott JD2. Abdom Radiol (NY). 2018 Jul 2. doi: 10.1007/s00261-018-1669-y. (in press)
- OBJECTIVE. The purpose of this study was to determine the rate of malignancy in inci- dentally detected bilateral adrenal masses in patients with no known history of cancer.
CONCLUSION. No case of malignancy was found in 322 incidentally detected bilateral adrenal nodules at CT of patients without known cancer. Imaging follow-up of such lesions may be unnecessary.
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? Corwin MT et al. AJR 2018; 210:780–784 - “The differential diagnosis of bilateral adrenal masses without gross fat includes bilateral adenomas, metastases, infection, hemorrhage, lymphoma, pheochromocytoma, and adrenal cortical carcinoma. It is possible that the rate of malignancy could differ between incidentally detected unilateral and bilateral lesions. Adrenal metastases have been reported to occur bilaterally in 49% of cases and lymphoma in 43%.”
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? Corwin MT et al. AJR 2018; 210:780–784 - “The most likely cause of the nodules in our study is adrenal adenoma. All nodules that were fully characterized at imaging proved to be adenomas in our study with the exception of two myelolipomas. Although the other nodules were presumed to be benign given imaging or clinical stability, the etiologic factors remained indeterminate because they were not further characterized and could represent other benign lesions, such as pheochromocytoma.”
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? Corwin MT et al. AJR 2018; 210:780–784 - “Our study adds to the growing body of evidence that small incidentally detected adrenal nodules in patients without a history of cancer are highly likely benign and may require no further imaging follow-up. Specifically, our findings suggest this approach applies to the case of bilateral nodules. This finding of our study is important because the increased use and resolution of CT have led to an increase in incidental findings unrelated to the original clinical indication. This can lead to extensive further cascades of imaging and interventional workups that can be costly and cause morbidity and psychologic stress.”
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? Corwin MT et al. AJR 2018; 210:780–784 - “We found no cases of malignancy in 322 incidentally detected bilateral adrenal nodules at CT examinations of 161 patients who had no known cancer. Imaging follow-up of such lesions may be unnecessary.”
Incidentally Detected Bilateral Adrenal Nodules in Patients Without Cancer: Is Further Workup Necessary? Corwin MT et al. AJR 2018; 210:780–784
- Flowchart for an adrenal mass
- Adrenal Washout Values
- “ The preferred work-up scheme for the indeterminate adrenal mass includes evaluation with a non-contrast CT. If a lesion is less than 10 HU < 10 on a non-contrast CT, it is a benign lipid-rich adenoma and no further work-up is needed. A lipid-poor adenoma can be differentiated from a metastasis utilizing CT wash-out patterns or MRI.”
Cross-sectional imaging work-up of adrenal masses Korivi BR, Elsayes KM World J Radiol. 2013 Mar 28; 5(3): 88–97 - “ The preferred work-up scheme for the indeterminate adrenal mass includes evaluation with a non-contrast CT. If a lesion is less than 10 HU < 10 on a non-contrast CT, it is a benign lipid-rich adenoma and no further work-up is needed. A lipid-poor adenoma can be differentiated from a metastasis utilizing CT wash-out patterns or MRI.”
Cross-sectional imaging work-up of adrenal masses Korivi BR, Elsayes KM World J Radiol. 2013 Mar 28; 5(3): 88–97. - “ Lipid-poor adenomas have an attenuation of more than 10 non-contrast HU and can be further characterized by their contrast enhancement and wash-out patterns. Only 30% of adenomas are lipid poor, which renders further characterization with contrast necessary. Adenomas tend to rapidly enhance after contrast administration and rapidly wash-out. Malignant lesions and pheochromocytomas also enhance rapidly but tend to exhibit slower wash-out patterns. Two methods have been developed to calculate wash-out patterns: the percentage of absolute contrast enhancement wash-out (ACEW) and the relative contrast enhancement wash-out (RCEW).
Cross-sectional imaging work-up of adrenal masses Korivi BR, Elsayes KM World J Radiol. 2013 Mar 28; 5(3): 88–97. - absolute contrast enhancement wash-out (ACEW)
• If a 15 min delay protocol is used, an ACEW value of 60% or higher has approximately 87% sensitivity and 94% specificity
• Note that ACEW measurements require a non-contrast HU measurement and in everyday practice, this is not always obtained. - relative contrast enhancement wash-out (RCEW).
• the percentage of RCEW can be calculated as: % RCEW = [(contrast-enhanced HU at 60 s - delayed contrast HU)/(contrast-enhanced HU at 60 s)] × 100.
• If a 15 min delay parameter is used, a RCEW of 40% or more has a sensitivity of 96% and specificity of 100% - OBJECTIVE. The purpose of this article is to retrospectively compare the accuracy of MRI and CT in characterizing lipid-poor adrenal adenomas with respect to lesion-attenuation values measured on unenhanced CT.
CONCLUSION. MRI is equivalent to CT for characterizing adenomas measuring 20 HU or less on unenhanced CT. However, MRI is inferior to CT for adenomas measuring more than 20 HU because of decreased MR sensitivity.
Characterization of Lipid-Poor Adrenal Adenoma: Chemical-Shift MRI and Washout CT Seo JM et al. AJR 2014; 202:1043–1050 - “Approximately 30% of adrenal adenomas are lipid-poor and cannot be differentiated from nonadenomas using unenhanced CT alone because these lipid-poor adenomas measure greater than 10 HU. Washout CT characterizes these lipid-poor adenomas with sensitivity of almost 100%.”
Characterization of Lipid-Poor Adrenal Adenoma: Chemical-Shift MRI and Washout CT Seo JM et al. AJR 2014; 202:1043–1050
- “Adrenal cortical hyperplasia manifests radiologically as the nonmalignant growth, or enlargement of the adrenal glands, specifically the cortex, although the cortex cannot be definitively identified by conventional imaging. Controlled by the pituitary gland, the adrenal cortex drives critical processes, such as cortisol, mineralocorticoid, and sex hormone production. Any disruption in the multiple enzymes and hormones involved in these pathways may cause serious or life-threatening symptoms, often associated with anatomical changes of the adrenal glands. Diagnosis and treatment of adrenal cortical hyperplasia requires a thorough clinical evaluation. As imaging has become more robust, so has its role in the diagnosis and treatment of adrenal conditions. CT has been the primary modality for adrenal imaging due to reproducibility, temporal and spatial resolution and broad access. MRI serves a complimentary role in adrenal imaging and can be used to further evaluate indeterminate CT findings or serve as an adjunct tool without the use of ionizing radiation. Ultrasound and fluoroscopy (genitography) are most commonly used in children and fetuses to evaluate congenital adrenal hyperplasia.”
Adrenal Cortical Hyperplasia: Diagnostic Workup, Subtypes, Imaging Features and Mimics. Agrons M et al. Br J Radiol. 2017 Jul 14:2017030 doi: 10.1259/bjr.20170330 - People with CAH lack one of the enzymes (proteins that cause chemical changes in the body), steroid 21-hydroxylase. This results in low production of the hormone that helps the body respond to stress (cortisol), and in most cases of classic CAH they lack another hormone needed to retain sodium (salt). This imbalance causes over-production of sex hormones (in males androgens, and in females, estrogens). CAH can be severe (classic) and diagnosed in the newborn, but it can also be mild (nonclassic) and not show up until later childhood, adolescence or adulthood.
- “People with CAH lack one of the enzymes (proteins that cause chemical changes in the body), steroid 21-hydroxylase. This results in low production of the hormone that helps the body respond to stress (cortisol), and in most cases of classic CAH they lack another hormone needed to retain sodium (salt). This imbalance causes over-production of sex hormones (in males androgens, and in females, estrogens). CAH can be severe (classic) and diagnosed in the newborn, but it can also be mild (nonclassic) and not show up until later childhood, adolescence or adulthood.”
Congenital adrenal hyperplasia Deborah P Merke, Stefan R Bornstein www.thelancet.com Vol365 June18,2005 - “Based on a review of autopsy series of approximately 35,000 subjects, the prevalence of ACH is estimated to be 0.51%, increasing with age. Hyperplasia can manifest as either a diffuse process involving the entire adrenal(s) or as nodular hyperplasia. Nodular hyperplasia is usually multifocal and bilateral, also increasing in prevalence with age. In a series of 113 consecutive adult necropsies, the adrenals were examined histologically and 35% were described as normal, 50% as having mild nodularity, and the remainder as having distinct nodularity. The average age of patients with distinct nodularity was 65 years versus 50 years for the normal group. This study demonstrated that an increasingly nodular appearance of the adrenal can occur with age.”
From the Radiologic Pathology Archives: Adrenal Tumors and Tumor-like Conditions in the Adult: Radiologic-Pathologic Correlation Grant E. Lattin, Jr et al. RadioGraphics 2014 34:3, 805-829
- “Imaging characteristics of adrenal tumors on CT scan predict benign pathology 100% of the time. Regardless of size, when interpreted as benign on CT scan, laparoscopic adrenalectomy, if technically feasible, should be the technique used when surgery is offered, or close surveillance may be a safe alternative.”
Computed Tomography in the Management of Adrenal Tumors: Does Size Still Matter? Azoury SC, Nagarajan N, Young A, Mathur A, Prescott JD, Fishman EK, Zeiger MA J Comput Assist Tomogr. 2017 Jan 20 [Epub ahead of print] - METHODS: A retrospective review was conducted of patients who underwent unilateral adrenalectomy for an adrenal mass between January 2005 and July 2015. Tumors were classified as benign, indeterminate, or malignant based on preoperative CT findings.
RESULTS: Of 697 patients who underwent unilateral adrenalectomy, 216 met the inclusion criteria. Pathology was benign in 88.4%, indeterminate in 2.3%, and malignant in 9.3%, with a median tumor diameter of 2.7 cm (interquartile range, 1.7-4.1 cm) and 9.5 cm (interquartile range, 7.1-12 cm) in the benign and malignant groups, respectively (P < 0.001). Of the tumors with benign features on CT, 100% (143/143) had benign final pathology.”
Computed Tomography in the Management of Adrenal Tumors: Does Size Still Matter? Azoury SC, Nagarajan N, Young A, Mathur A, Prescott JD, Fishman EK, Zeiger MA J Comput Assist Tomogr. 2017 Jan 20 [Epub ahead of print] 
- Adrenal Gland Imaging: Pitfalls
- Pseudolesions
- accessory spleen
- celiac plexus
- lymph nodes
- gastric fundal diverticula,
- venous varices
- renal lesions - Adrenal Gland Imaging: Pitfalls
- Pheochromocytoma is a great mimicker especially when it presents as an incidental finding
- Collision tumors that have been defined as representing 2 pathologically distinct lesions (such as a benign and a malignant lesion), giving the appearance of a single lesion. The benign features of portions of a conglomerate lesion (ie, intralesional lipid) could lead to the false conclusion that the entire mass is benign. - Adrenal Gland Imaging: Pitfalls
- Metastases to the adrenal from renal cell carcinoma or hepatoma can be confused with pheochromocytoma or even adenoma based on washout values.
- Macroscopic fat in an adrenal mass is effectively diagnostic of adrenal myelolipoma; however, smaller amounts of fat can be present within myelolipomatous metaplasia of adrenal cortical neoplasms such as degenerated adenomas and adrenal cortical carcinomas. - “Although incidentally detected adrenal nodules are most commonly benign adrenal adenomas, accurate imaging char- acterization is important, as the risk of malignancy increases substantially in patients with a history of primary malignancy and in adrenal nodules measuring more than 4 cm.”
Pitfalls in Adrenal Imaging Taner AT et al. Semin Roentgenol. 2015 Oct;50(4):260-72.
- “Adrenal adenoma is the most common AI, and 70% of cases contain significant amounts of intracellular lipid. The presence of intracellular lipid (i.e., lipid-rich adenoma) allows differentiation from lipid-poor adenomas and nonadenomas with high specificity. Adrenal mass characterization with the use of CT requires placing an ROI over one-half to two-thirds of the surface area of the mass while avoiding areas of necrosis and calcification.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “Myelolipomas contain macroscopic fat, which is characterized by attenuation of less than −20 HU on CT and signal dropout on fat-suppressed MRI sequences . Macroscopic fat rarely can be seen in adrenal adenomas, adrenocortical carcinomas (ACCs), and pheochromocytomas, and large myelolipomas may be difficult to distinguish from liposarcomas .”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “The majority of AIs are benign in patients with no previously known malignancy. Even in patients with a primary nonadrenal malignancy known to be associated with a high frequency of adrenal metastases, only 50% of AIs are caused by metastatic disease.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “Approximately 30% of adenomas, which are the most common AIs, are lipid poor and cannot be distinguished from malignancy on unenhanced CT. Routine CECT cannot distinguish adenomas from nonadenomas because of the overlap in attenuation values .”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “Although most patients with AIs have nonfunctioning adenomas (80%), 5–10% have subclinical or early Cushing syndrome, 5% have pheochromocytoma, and 1% have aldosteronoma.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “The ACR algorithm considers biochemical (hormonal) evaluation, but the document states that routine hormonal evaluation of all incidentalomas “would be costly and is not routinely performed by many physicians” . Furthermore, biochemical evaluation should be considered only “if there are clinical signs or symptoms of adrenal hyperfunction”. This view is contrary to the preponderance of clinical recommendations in the endocrine literature.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “Because pheochromocytomas have nonspecific features on imaging, and because clinical expertise in diagnosing pheochromo- cytomas may vary, it has been suggested that all adrenal masses be screened for catechol- amine excess . Plasma metanephrines have similar sensitivity and specificity for pheochromocytoma as urine fractionated metanephrines and may be considered as the first screening test.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “AIs may develop cortisol hyperfunction over time, even if they are not hormonally active at the time of the initial evaluation. The risk of a mass larger than 2.4 cm becoming hormonally active is 17% at 1 year, 29% at 2 years, and 47% at 5 years. There is good agreement among the clinical recommendations that individuals with benign non- functioning AIs measuring greater than 2.4 cm should obtain annual hormonal testing for Cushing syndrome for 4 years. Other than consideration of initial biochemical evaluation of patients with signs or symptoms of adrenal hyperfunction, the ACR guidelines do not recommend long-term follow-up of hormonal function.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “Therefore, all incidentally detected adrenal masses 1 cm or larger should undergo biochemical evaluation, unless the imaging features are diagnostic of a nonfunctional process (e.g., myelolipoma or cyst). In addition to the initial biochemical evaluation, an additional yearly follow-up examination to evaluate cortisol secretion should be performed for masses larger than 2.4 cm or if such an examination is clinically indicated on the basis of new signs or symptoms.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 - “Radiologists play a key role in characterizing adrenal masses as benign or malignant and in recommending further imaging and biochemical evaluation for AIs. Until greater agreement is reached in the medical community, it would be prudent for diagnostic radiologists to dis- cuss these topics with their endocrinology colleagues to develop a local consensus.”
Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178
- “Adrenal incidentalomas (AIs) are found in approximately 4% of patients undergoing abdominal imaging, with peak prevalence in the sixth and seventh decades of life. Detection of AI warrants clinical, biochemical, and radiological evaluation to establish its secretory status and risk of malignancy. Careful review of the lipid content, size, and imaging phenotype of an adrenal mass is needed to evaluate the risk for malignancy. Identification of an AI may be an opportunity to identify an underlying secretory tumor that may have been otherwise unrecognized. A practical approach to investigation and follow-up of AIs is presented in this article.”
Adrenal Incidentalomas: A Disease of Modern Technology Offering Opportunities for Improved Patient Care. Ioachimescu AG et al. Endocrinol Metab Clin North Am. 2015 Jun;44(2):335-354.
- “The problem at hand is that approximately 85% of adrenal incidentalomas are nonfunctional and asymptomatic. Most are benign adenomas. The roughly 70% that are lipid-rich are easily characterized. However, the 30% that are lipid-poor are difficult to distinguish from ACC. Epidemiologic statistics overwhelmingly indicate that most of these lipid-poor adrenal incidentalomas are also benign.”
Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
Mazzaglia PJ
Surg Clin N Am 94 (2014) 625–642 - “Current guidelines issued by the National Institutes of Health (NIH) regarding nonfunctioning incidentalomas suggest resection of lesions larger than or equal to 4 cm. Based on these guidelines and the prevalence of ACC, most laparoscopic adrenalectomies performed for biochemically silent lesions show benign adrenal adenomas. The National Italian Study Group on Adrenal Tumors found that a 4 cm adrenal lesion had a 93% sensitivity but only 24% specificity for ACC.”
Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
Mazzaglia PJ
Surg Clin N Am 94 (2014) 625–642 - “There are two ways to calculate contrast washout. The first is called absolute percentage washout (APW) and the second is called relative percentage washout (RPW). APW requires a noncontrast HU measurement. APW is calculated using the formula ([enhanced HU−delayed HU]÷[enhanced HU−noncontrast HU]) × 100. Frequently, only contrast and delayed images are performed so an APW cannot be calculated. In these cases, the RPW must be used and is calculated as ([enhanced HU−delayed HU]÷enhanced HU) × 100. Because the APW includes the noncontrast measurement, it is considered more accurate.”
Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
Mazzaglia PJ
Surg Clin N Am 94 (2014) 625–642 - “The most recent and possibly fastest growing segment of adrenal imaging is PET-CT scanning (Fig. 6). Using PET with fludeoxyglucose F 18 (18F FDG-PET), studies have shown very high accuracy for detecting adrenal malignancies, with sensitivity as high as 100% and specificity between 87% and 97%. The FDG uptake does not significantly differ for lipid-rich versus lipid-poor adenomas, and the sensitivity and specificity for lipid-poor adenomas are 98.5% and 92%, respectively Only 5% of normal adrenals are seen on PET alone, whereas 68% are seen on PET-CT.”
Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
Mazzaglia PJ
Surg Clin N Am 94 (2014) 625–642 - “The rate of false-positive PET scan for nonfunctioning adrenal incidentalomas is 5% due to inflammatory lesions, such as sarcoid and tuberculosis, or adrenocortical hyperplasia. False-negative PET is rare but can occur if there has been extensive hemorrhage or necrosis, or if the adrenal lesion is a metastasis from a primary that is not FDG-avid.”
Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
Mazzaglia PJ
Surg Clin N Am 94 (2014) 625–642 - “On noncontrast CT, a feature often associated with ACCs includes central necrosis, which can occur as the tumor outstrips its blood supply. Radiographically, this will produce heterogeneity of the attenuation coefficient. Approximately 30% of ACCs contain calcifications. It is rare to see macroscopic fat.53 On contrast-enhanced CT, there is expected imaging heterogeneity . Usually, the absolute and relative washout is less than it is for benign adenomas; however, there are rare case reports of ACCs with benign washout characteristics.”
Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
Mazzaglia PJ
Surg Clin N Am 94 (2014) 625–642
- “ Adrenal incidentalomas are commonly noted on abdominal cross-sectional imaging studies. Most of these lesions are benign, non-functional adrenal adenomas. Certain adrenal lesions have such characteristic radiologic findings that their diagnosis can be made with virtual certainty.”
Radiology of the Adrenal
Udelsman R, Fishman EK
Endorinol Metab Clin North Am 2000 Mar 29(1);27-42
- “ At routine contrast-enhanced MDCT, adrenal masses with irregular margins or a thick enhancing rim are likely to be malignant. Smooth margins and homogeneous density can be seen in both benign and malignant adrenal masses and are insufficient for characterization.”
Morphologic Features of 211 Adrenal Masses at Initial Contrast-Enhanced CT: Can We Differentiate Benign From Malignant Lesions Using Imaging Features Alone-
Song JH et al.
AJR 2013; 201:1248-1253 - “ For individual morphologic features in diagnosing malignancy, irregular margins had 30-33% sensitivity and 95-96% specificity and an enhancing rim had 5-13% sensitivity and 98-99% specificity.”
Morphologic Features of 211 Adrenal Masses at Initial Contrast-Enhanced CT: Can We Differentiate Benign From Malignant Lesions Using Imaging Features Alone-
Song JH et al.
AJR 2013; 201:1248-1253 - “ Notably, no malignant lesions occurred in patients without a known history of cancer.”
Morphologic Features of 211 Adrenal Masses at Initial Contrast-Enhanced CT: Can We Differentiate Benign From Malignant Lesions Using Imaging Features Alone-
Song JH et al.
AJR 2013; 201:1248-1253
- Incidental Adrenal Nodule
1. 3-7% of all CT exams
2. Noncancer patients
- adenoma (80%)
- myelolipoma (6%)
- pheochromocytoma (3%) - Adrenal Hyperplasia
- Normal adrenal limbs should be ? 5 mm
- Can cause Cushing’s syndrome or Conn syndrome - Adrenal Insufficiency
- Bilateral hemorrhage à adrenal insufficiency
- Nonspecific symptoms
- Fatigue, weakness, muscle/joint pain
- Abdominal pain, vomiting, diarrhea
- Depression, behavioral changes
- Hypotension - Adrenal Pseudocyst
- Sequela of previous hemorrhage
- Unilocular or multilocular
- Calcification in 43%
- Pseudocyst can be present with an adrenal tumor
- “ The prevalence of incidental adrenal masses in abdominal CT is approximately 4%, ranging from 0.2% in patients 20-29 years old to 7% in patients over 70 years old.”
Prevalence of adrenal incidentaloma in a contemporary computerized tomography series.”
J Endocrinol Invest
2006; 29:298-302
- Adrenal Pseudocyst
-Sequela of previous hemorrhage
-Unilocular or multilocular
-Calcification in 43%
-Pseudocyst can be present with an adrenal tumor "The goal of imaging when an incidental adrenal mass is discovered is to differentiate a benign "leave alone" mass (eg.nonhyperfunctioning tumor,myelolipoma,hemorrhage,cyst) from a mass that warrants treatment (eg, metastases, pheochromocytoma,adrenal cortical carcinoma)."
Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee
Berland LL et al.
J Am Coll Radiol 2010;7;754-773"This white paper which represents the collective experience of the Incidental Findings Committee, using a less formal process of repeated reviews and revisions of the draft document, does not represent official ACR policy. For these reasons, this white paper should not be used to establish the legal standard of care in any particular situation."
Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee
Berland LL et al.
J Am Coll Radiol 2010;7;754-773"The committee has used a consensus method based on repeated reviews and revisions of this document and a collective review and interpretation of relevant literature. This white paper provides guidance devloped by this committee for addressing incidental findings in the kidneys, liver , adrenal gland and pancreas."
Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee
Berland LL et al.
J Am Coll Radiol 2010;7;754-773- "All of the incidentally detected adrenal masses with a CT attenuation of >10 HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental mass appears to have a limited role in this patient cohort."
The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123 - "In conclusion, the results of our study show that none of the incidentally detected adrenal masses was malignant in patients with no known cancer. If an incidental adrenal mass appears benign on imaging and the patient has no known malignancy, follow-up imaging appears to have a limited role."
The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123 - "All of the incidentally detected adrenal masses with a CT attenuation of >10 HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental mass appears to have a limited role in this patient cohort."
The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123 - "In conclusion, the results of our study show that none of the incidentally detected adrenal masses was malignant in patients with no known cancer. If an incidental adrenal mass appears benign on imaging and the patient has no known malignancy, follow-up imaging appears to have a limited role."
The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123 - "All of the incidentally detected adrenal masses with a CT attenuation of >10HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental adrenal mass appears to have a limited role in this patient cohort." The Incidental Indeterminate Adrenal Mass on CT (> 10HU) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123
- Objective: The objective of our study was to determine whether follow-up imaging evaluation is necessary for incidentally discovered indeterminate adrenal lesions (>10HU) on CT in patients with no known malignancy. Conclusion:All of the incidentally detected adrenal masses with a CT attenuation of >10HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental adrenal mass appears to have a limited role in this patient cohort.
- "There are only slight differences in attenuation of adrenal nodules measured on scans obtained with different scanners." Adrenal Lesions: Attenuation measurement Differences between CT Scanners Hahn PF et al. Radiology 2006; 240:458-463.
- Absolute Contrast Enhancement Washout
-[(E-D/E-U)] x 100
- Where E is the enhanced attenuation value, D is the delayed enhancement value, and U is the unenhanced value