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Everything you need to know about Computed Tomography (CT) & CT Scanning

May 2018 Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ May 2018

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Adrenal

    • “Adrenal pheochromocytomas may develop in 25%–30% of VHL cases The mean age of onset is 27 years (range, 5–58 years). VHL- associated pheochromocytomas manifest more commonly in boys , and 20%–50% may be bilateral.The risk of developing a second tumor increases with age, with studies reporting a 50% risk of a second tumor at 30 years after the initial diagnosis; 1%–5% of these tumors are malignant.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Extra-adrenal pheochromocytomas/paragangliomas may be seen in 15% of VHL cases at various sites along the sympathetic chain in the abdomen, thorax, or head and neck. Patients may be asymptomatic or experience classic symptoms such as paroxysmal or refractory hypertension, palpitations, headaches, sweating, and hypertensive crises. A diagnosis of a pheochromocytoma is usually confirmed on the basis of biochemical abnormalities, including elevated plasma metanephrine and 24-hour urinary catecholamine levels.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “A significant subset of pheochromocytomas mimics adenomas on absolute or relative percentage washout calculations. However, nodules with venous phase enhancement of 85 HU or more are much more likely to be pheochromocytomas than adenomas, regardless of whether the lesion shows absolute or relative percentage washout compatible with a lipid-poor adenoma. The typical values of absolute and relative percentage washout of adrenal adenoma should be interpreted along with the venous phase enhancement value to avoid potential misdiagnoses.” 


      Pheochromocytomas Versus Adenoma: Role of Venous Phase CT Enhancement 
Mohammed MF et al.
AJR 2018; 210:1073–1078
    • “As such, we suggest a cutoff of 85 HU to recommend further investigation to exclude pheochromocytoma even if an incidental, clinically silent adrenal nodule meets the washout criteria of adenoma. This process would in turn help avoid duplicative imaging and decrease costs, waiting times, and additional follow-up adrenal protocol imaging.” 


      Pheochromocytomas Versus Adenoma: Role of Venous Phase CT Enhancement 
Mohammed MF et al.
AJR 2018; 210:1073–1078
    • “In our study, a venous phase enhancement value of 85 HU or more was detected in 30 pheochromocytomas (88.2%) and seven ad- enomas (16.3%). By contrast, a venous phase enhancement value below 85 HU was detect- ed in four pheochromocytomas (11.8%) and 36 adenomas (83.7%) .A threshold of 85 HU identi fied pheochromocytoma with 88.2% sensitivity and 83.7% specificity.” 


      Pheochromocytomas Versus Adenoma: Role of Venous Phase CT Enhancement 
Mohammed MF et al.
AJR 2018; 210:1073–1078
    • “On assessment of peak venous enhancement, a cutoff of 85 HU provides a highly sensitive and specific threshold in evaluation of incidental adrenal nodules. Exceeding this threshold favors the diagnosis of pheochromocytoma rather than adenoma but is not a threshold for exclusion of adenoma or definitive diagnosis of pheochromocytoma.” 


      Pheochromocytomas Versus Adenoma: Role of Venous Phase CT Enhancement 
Mohammed MF et al.
AJR 2018; 210:1073–1078
Contrast

    • OBJECTIVE. Most diagnostic imaging centers ask patients to fast for 4–6 hours before contrast-enhanced CT. Previous studies have shown that prolonged fasting can be harmful. In addition, manufacturers of contrast agents claim that there is no special preparation needed before examination. The aim of this study was to evaluate the effects of preparative fasting on contrast-enhanced CT at a cancer center. 


      CONCLUSION. In this sample of patients with cancer undergoing contrast-enhanced CT, very few adverse symptoms were reported regardless of preparative fasting. These results support the idea that preparation for contrast-enhanced CT can be simplified, decreasing the discomfort and inconvenience experienced by patients.

      
Preparative Fasting for Contrast- Enhanced CT in a Cancer Center: A New Approach 
Paula N. V. P. Barbosa et al.
AJR 2018; 210:941–947
    • “In this sample of patients with cancer undergoing contrast-enhanced CT, very few adverse symptoms were reported regardless of preparative fasting. These results support the idea that preparation for contrast-enhanced CT can be simplified, decreasing the discomfort and inconvenience experienced by patients.”

      
Preparative Fasting for Contrast- Enhanced CT in a Cancer Center: A New Approach 
Paula N. V. P. Barbosa et al.
AJR 2018; 210:941–947
    • “The historical basis for preparative fasting for contrast-enhanced CT is the concern over pulmonary aspiration of gastric contents and aspiration pneumonia after vomiting. Though this may have been a significant clinical issue for first-generation hyperosmolar contrast agents, which caused nausea and vomiting in 4.58% and 1.84% of cases, respectively, the introduction of nonionic low-osmolarity contrast agents has decreased the frequency of vomiting to approximately 0.3%.”


      Preparative Fasting for Contrast- Enhanced CT in a Cancer Center: A New Approach 
Paula N. V. P. Barbosa et al.
AJR 2018; 210:941–947
    • “Most diagnostic imaging centers ask patients to fast for 4–6 hours before contrast- enhanced examinations. However, patients who abstain from food and liquids for prolonged periods also tend to be more anxious and less cooperative during the examination, in addition to being more susceptible to adverse reactions to the IV contrast medium.”


      Preparative Fasting for Contrast- Enhanced CT in a Cancer Center: A New Approach 
Paula N. V. P. Barbosa et al.
AJR 2018; 210:941–947
    • “The present findings revealed no clinical- ly and statistically significant differences in the frequency of adverse reactions in outpatients with cancer undergoing contrast-enhanced CT with or without preparative fasting. These findings, together with our clinical experience at an imaging center, support the guidelines provided by the French Radiology Society, which do not recommend fasting before contrast-enhanced CT scans, because the absence of adequate nutrition and hydration may increase the likelihood of adverse reactions to contrast agent administration.”


      Preparative Fasting for Contrast- Enhanced CT in a Cancer Center: A New Approach 
Paula N. V. P. Barbosa et al.
AJR 2018; 210:941–947
    • “In the present investigation, patients also reported unexpected symptoms after contrast agent administration, such as flushing, dizziness, ear pruritus, tingling, tremor, pain at the injection site, tachycardia, and headaches. These manifestations, referred to as “other unexpected symptoms,” were significantly associated with fasting. Though infrequent, these symptoms are likely to contribute to patient irritability and uncooperativeness.”


      Preparative Fasting for Contrast- Enhanced CT in a Cancer Center: A New Approach 
Paula N. V. P. Barbosa et al.
AJR 2018; 210:941–947
Kidney

    • “Multicentric renal cysts and clear cell RCCs
may manifest in more than two-thirds of VHL cases. Even grossly normal renal parenchyma may demonstrate hundreds
of microscopic renal cysts and tumors. The cystic lesions may be a combination of simple benign cysts, complex atypical cysts with epithelial hyperplasia/cytologic atypia, or cystic RCCs.The number and size of the cysts in VHL have not been shown to be associated with malignant potential. Patients may be asymptomatic despite the manifestation of a large number of cysts.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “VHL is characterized by the development of a clear cell RCC histologic subtype. The prevalence of RCC in VHL varies from 25% to 45%, with the frequency increasing with age. VHL-related RCCs tend to develop at a much younger age compared with that of sporadic RCCs. The mean age of onset for VHL-related RCCs is 39 years (range, 
 13–70 years), and clear cell RCCs are frequently bilateral.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “It should be noted that bilateral clear cell RCCs on their own are not diagnostic of VHL, as other hereditary renal tumor syndromes and rarely even sporadic tumors may manifest as bilateral multifocal tumors. However, the presence of bilateral or multifocal clear cell RCCs or tumors in patients younger than 50 years of age is an indication for VHL genetic screening.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
Pancreas

    • “As for the evaluation of the tumor-vascular circumferential contact, our results show that the progression of tumor-vascular contact on MDCT was frequent after CRT, which is concordant with the findings of previous studies. However, the frequency of progression in tumor contact did not show a significant difference between resectable and unresectable diseases.”


      Preoperative MDCT Assessment of Resectability in Borderline Resectable Pancreatic
Cancer: Effect of Neoadjuvant Chemoradiation Therapy
Joo I et al.
AJR 2018; 210:1059–1065
    • “Our study also found that patients who re- ceived neoadjuvant CRT showed a higher fre- quency of local resectability than did those who underwent upfront surgery (60% [9/15] vs 20% [3/15]), which is in good agreement with recent studies. Given the relatively high resectability after neoadjuvant CRT but insufficient accuracy of MDCT, surgical exploration might be considered even for those considered to have imaging-based unresectable diseases after neoadjuvant CRT.”

      
Preoperative MDCT Assessment of Resectability in Borderline Resectable Pancreatic
Cancer: Effect of Neoadjuvant Chemoradiation Therapy
Joo I et al.
AJR 2018; 210:1059–1065
    • “In conclusion, in patients with borderline resectable pancreatic cancers, neoadjuvant CRT did not significantly decrease the diagnostic performance of MDCT for the prediction of local resectability. However, by considering the interval changes in imaging features during CRT, MDCT may provide better sensitivity for locally resectable diseases.”


      Preoperative MDCT Assessment of Resectability in Borderline Resectable Pancreatic
Cancer: Effect of Neoadjuvant Chemoradiation Therapy
Joo I et al.
AJR 2018; 210:1059–1065
    • “Patients with VHL can develop pancreatic cysts, serous cystadenomas, and pancreatic NETs. Pancreatic cysts are com- mon in VHL and may be seen in 42% of cases (range, 7%–72%). These are typically multiple and usually asymptomatic. Interestingly, pancreatic cysts may be the only manifestation in about 12% of patients at the time of initial VHL diagnosis.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Serous cystadenomas occur in 11% of patients (range, 9%–17%) At histopathologic analysis, serous cystadenomas demonstrate well- demarcated multilocular clusters of small cysts, separated by thin fibrous septa. These cystic lesions are lined by cuboidal cells, without mucin or papillary structures. Both pancreatic cysts and serous cystadenomas tend to be asymptomatic, but larger lesions may cause nonspecific abdominal pain, and extensive cystic lesions replacing most of the pancreas may result in pancreatic insufficiency and diabetes mellitus.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Pancreatic NETs develop in 15% of patients with VHL (range, 9%–17%) . The mean age of onset is 35 years, but NETs have been reported in patients as young as 13 years of age. About 53% of VHL-associated pancreatic NETs are multiple. Although any part of the pancreas may be involved, they are more common in the head and uncinate process of the pancreas. Pancreatic NETs associated with VHL manifest at a much younger age compared with that of sporadic NETs, and they are more commonly multifocal.The vast majority of these pancreatic NETs are nonfunctional tumors.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Considering that less than 20% of pancreatic NETs associated with VHL are malignant, a conservative approach with a “watch-and-wait” strategy is an important part of the management of these tumors. Studies have shown that about 40% of NETs in VHL may be stable or even decrease in size. Surgical resection may be appropriate for pancreatic NETs in VHL when the tumor size is greater than 3 cm (or >2 cm for lesions in the head of the pancreas), the tumor doubling time is less than 500 days, there is a mutation in exon 3, or there is suspicion of regional nodal metastases.”


      Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • OBJECTIVE. The purpose of this study is to evaluate the diagnostic performance of MDCT in assessing tumor resectability in patients with borderline resectable pancreatic cancers after receiving neoadjuvant chemoradiation therapy (CRT) in comparison with those undergoing upfront surgery.

      
CONCLUSION.
      In patients with borderline resectable pancreatic cancers, neoadjuvant CRT did not signifi- cantly decrease the performance of MDCT for the prediction of local resectability. However, by considering post-CRT changes, such as nonprogression in tumor-vascular contact, MDCT may provide better sensitivity for locally resectable disease. 


      Preoperative MDCT Assessment of Resectability in Borderline Resectable Pancreatic
Cancer: Effect of Neoadjuvant Chemoradiation Therapy
Joo I et al.
AJR 2018; 210:1059–1065
Practice Management

    • “The primary purpose of scout views on cross-sectional CT and MRI examinations is to prescribe the imaging slices and display slice locations. For this reason, radiologists often ignore the scout images. However, it is not unusual for a pathologic abnormality to be visible on the initial scout images but then excluded from the subsequent diagnostic images, often because of the relatively larger FOV of the scout images. Scout views have been shown to contribute significantly to diagnosis. A systematic neglect of the scout views on cross-sectional imaging studies can result in important diagnoses being missed. A simple and effective remedy for this type of bias is to routinely review the scout images and include a field in the report template labeled “Scout views.”

      
Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
    • “Errors in radiology are broadly classified 
into perceptual errors and interpretive errors. Perceptual errors account for 60–80% of errors and occur when an abnormality is present on a diagnostic image but not seen by the interpreting radiologist Interpretive errors constitute the remaining 20–40% of errors and occur when an abnormality is identified on an image but its meaning or importance is incorrectly interpreted.”

      
Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
    • “A heuristic is a mental shortcut that allows rapid problem solving based on assumptions and past experiences. Cognitive bias is a systematic error in reasoning or judgment that can be the result of failed heuristics. Cognitive biases can lead to both perceptual and interpretive errors. Perceptual error is an error that occurs when an abnormality is present on a diagnostic image but not seen by the interpreting radiologist. Interpretive error is an error that occurs when an abnormality is identified on an image but its meaning or importance is incorrectly interpreted. Diagnostic error is defined as a diagnosis that is missed, wrong, or delayed, which can be the result of either perceptual or interpretive errors.” 


      Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
    • “It has been observed that the detection rate for second and third abnormalities after one abnormality has been detected can decrease to approximately 50%, a cognitive bias termed “satisfaction of search”. This bias occurs when the visual search pattern is discontinued after identification of an abnormality that can explain the patient’s symptom and the interpreting radiologist is satisfied that the diagnosis has been determined.” 


      Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
    • “Diagnostic errors commonly arise from faulty heuristics and cognitive biases that all radiologists share. Such biases can produce predictable patterns of misdiagnoses. Awareness of the spectrum of cognitive biases is an important step toward a comprehensive strategy to learn from diagnostic errors and ultimately improve patient care.” 


      Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
    • “The practice of reinterpreting imaging ex- aminations performed at outside institutions is becoming commonplace at academic centers because of a relatively high rate of discrepancies affecting patient care. Error rates as high as 41% have been reported during the reinterpretation of outside CT and MRI examinations in patients with head and neck cancer at an academic center.” 


      Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
    • “Availability bias refers to the tendency for diagnostic assessments to be unduly influenced by easily recalled experiences 
For radiologists, memorable cases can exert an undue effect on the interpretation of sub- sequent cases. Prior cases may be easier to recall if they were recently interpreted, associated with an unusual diagnosis, or associated with a personal error. Such cases may exert a disproportionate effect on diagnostic thinking compared with other more-routine cases or cases from the remote past.” 


      Heuristics and Cognitive Error in Medical Imaging 
Itri JN, Patel SH
AJR 2018; 210:1097–1105
Syndromes in CT

    • “Von Hippel–Lindau syndrome (VHL) is a hereditary tumor syndrome, arising owing to germline mutations in the VHL tumor suppressor gene, located on the short arm of chromosome 3. VHL is an autosomal dominant disorder, with a prevalence of around one in 36 000 and one in 50 000 live births. Around 80% of patients with VHL inherit the disorder from an affected parent, while it may arise de novo in 20%.The mean age of initial tumor diagnosis in VHL is 26 years (range, 1–70 years).”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “VHL is a highly penetrant disease, with more than 90% of patients developing symptoms by 65 years of age. Patients may develop multiple benign and malignant tumors involving various organ systems, including retinal hemangioblastomas (HBs), central nervous system (CNS) HBs, endolymphatic sac tumors, pancreatic neuroendocrine tumors (NETs), pancreatic cystadenomas, pancreatic cysts, clear cell renal cell carcinomas (RCCs), renal cysts, pheochromocytomas, paragangliomas, and epididymal and broad ligament cystadenomas.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Patients may develop multiple benign and malignant tumors involving various organ systems, including retinal HBs, CNS HBs, endolymphatic sac tumors, pancreatic NETs, pancreatic cystadenomas, pancreatic cysts, clear cell RCCs, renal cysts, pheochromocytomas, paragangliomas, and epididymal and broad ligament cystadenomas.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Missense mutations (27%–52%) are the most common type of germline mutations reported
in VHL. However, a wide spectrum of germline mutations have been described, including frame- shift mutations, nonsense mutations, large or microdeletions, gene rearrangements, in-frame deletions or insertions, and splice site mutations. Somatic inactivation of the wild-type allele may arise owing to allelic loss, hypermethylation, or point mutations.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    •  “VHL is associated with multiple tumors affecting various organs. A VHL diagnosis can be made clinically when the characteristic clinical history and findings have manifested. The clinical diagnosis of VHL can be made in the following circumstances: (a) in a patient with a family history of VHL and at least one of the characteristic VHL-related tumors (eg, retinal HBs, CNS HBs, clear cell RCCs, pancreatic NETs, and endolymphatic sac tumors); (b) in the presence of two or more retinal or CNS HBs; or (c) in the presence of one retinal or CNS HB, plus at least one of the characteristic VHL-related visceral tumors, excluding renal and epididymal cysts.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • Table 1: VHL Manifestations
      • Retina
      • Retinal HBs
      • CNS
      • Cerebellar and spinal HBs
      • Head and Neck
      • Endolymphatic sac tumors
      • Pancreas
      • Pancreatic cysts
      • Serous cystadenomas
      • Pancreatic NETs
      • Kidney
      • Renal cysts
      • Clear cell RCCs
      • Adrenal gland
      • Pheochromocytoma 

    • “Multicentric renal cysts and clear cell RCCs
may manifest in more than two-thirds of VHL cases. Even grossly normal renal parenchyma may demonstrate hundreds
of microscopic renal cysts and tumors. The cystic lesions may be a combination of simple benign cysts, complex atypical cysts with epithelial hyperplasia/cytologic atypia, or cystic RCCs.The number and size of the cysts in VHL have not been shown to be associated with malignant potential. Patients may be asymptomatic despite the manifestation of a large number of cysts.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “VHL is characterized by the development of a clear cell RCC histologic subtype. The prevalence of RCC in VHL varies from 25% to 45%, with the frequency increasing with age. VHL-related RCCs tend to develop at a much younger age compared with that of sporadic RCCs. The mean age of onset for VHL-related RCCs is 39 years (range, 
 13–70 years), and clear cell RCCs are frequently bilateral.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “It should be noted that bilateral clear cell RCCs on their own are not diagnostic of VHL, as other hereditary renal tumor syndromes and rarely even sporadic tumors may manifest as bilateral multifocal tumors. However, the presence of bilateral or multifocal clear cell RCCs or tumors in patients younger than 50 years of age is an indication for VHL genetic screening.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Patients with VHL can develop pancreatic cysts, serous cystadenomas, and pancreatic NETs. Pancreatic cysts are com- mon in VHL and may be seen in 42% of cases (range, 7%–72%). These are typically multiple and usually asymptomatic. Interestingly, pancreatic cysts may be the only manifestation in about 12% of patients at the time of initial VHL diagnosis.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Serous cystadenomas occur in 11% of patients (range, 9%–17%) At histopathologic analysis, serous cystadenomas demonstrate well- demarcated multilocular clusters of small cysts, separated by thin fibrous septa. These cystic lesions are lined by cuboidal cells, without mucin or papillary structures. Both pancreatic cysts and serous cystadenomas tend to be asymptomatic, but larger lesions may cause nonspecific abdominal pain, and extensive cystic lesions replacing most of the pancreas may result in pancreatic insufficiency and diabetes mellitus.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Pancreatic NETs develop in 15% of patients with VHL (range, 9%–17%) . The mean age of onset is 35 years, but NETs have been reported in patients as young as 13 years of age. About 53% of VHL-associated pancreatic NETs are multiple. Although any part of the pancreas may be involved, they are more common in the head and uncinate process of the pancreas. Pancreatic NETs associated with VHL manifest at a much younger age compared with that of sporadic NETs, and they are more commonly multifocal.The vast majority of these pancreatic NETs are nonfunctional tumors.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Considering that less than 20% of pancreatic NETs associated with VHL are malignant, a conservative approach with a “watch-and-wait” strategy is an important part of the management of these tumors. Studies have shown that about 40% of NETs in VHL may be stable or even decrease in size. Surgical resection may be appropriate for pancreatic NETs in VHL when the tumor size is greater than 3 cm (or >2 cm for lesions in the head of the pancreas), the tumor doubling time is less than 500 days, there is a mutation in exon 3, or there is suspicion of regional nodal metastases.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Adrenal pheochromocytomas may develop in 25%–30% of VHL cases The mean age of onset is 27 years (range, 5–58 years). VHL- associated pheochromocytomas manifest more commonly in boys , and 20%–50% may be bilateral.The risk of developing a second tumor increases with age, with studies reporting a 50% risk of a second tumor at 30 years after the initial diagnosis; 1%–5% of these tumors are malignant.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “Extra-adrenal pheochromocytomas/paragangliomas may be seen in 15% of VHL cases at various sites along the sympathetic chain in the abdomen, thorax, or head and neck. Patients may be asymptomatic or experience classic symptoms such as paroxysmal or refractory hypertension, palpitations, headaches, sweating, and hypertensive crises. A diagnosis of a pheochromocytoma is usually confirmed on the basis of biochemical abnormalities, including elevated plasma metanephrine and 24-hour urinary catecholamine levels.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
    • “VHL is a familial cancer syndrome caused by
a mutation in the VHL tumor suppressor gene, mapped on human chromosome 3p25. Patients with VHL are at risk for developing numerous benign and malignant tumors that affect multiple organs. While some of the VHL-related manifestations such as renal and pancreatic cysts are frequently asymptomatic, other manifestations such as retinal and CNS HBs, RCCs, pheochromocytomas, and pancreatic NETs may be associated with significant morbidity and mortality. Early detection plays a key role in the optimal management of this condition.”
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review 
Ganeshan D et al.
 RadioGraphics 2018 (in press)
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