Imaging Pearls ❯ Pancreas ❯ Metastases to the Pancreas
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- Purpose To determine whether renal cell carcinoma metastases (RCC-Mets) to the pancreas can be differentiated from pancreatic neuroendocrine tumors (PNETs) in patients with RCC on CT or MRI at presentation. Methods This retrospective study included patients with biopsy-proven RCC-Mets (n = 102) or PNETs (n = 32) at diagnosis or after nephrectomy for RCC. Inter-observer agreement (Cohen kappa) was assessed in 95 patients with independent readsby two radiologists, with discrepancies resolved by consensus for final analysis. The remaining 39 cases underwent consensus reads by two different radiologists for final analysis. The CT/MRI images were reviewed for number, size, regional distribution, parenchymal location (exophytic or intrapancreatic), contrast-enhancement, and enhancement pattern of pancreatic lesions in the available phases. Statistical tests were conducted using two sample t-tests and Pearson’s chi-squared test for numeric and categorical variables respectively.
Differentiation between renal cell carcinoma metastases to the pancreas and pancreatic neuroendocrine tumors in patients with renal cell carcinoma on CT or MRI
Marie‑Joy Nduwimana . Ceylan Colak . Cem Bilgin . Blake A. Kassmeyer . Candice M. Bolan . Christine O. Menias . Sudhakar K. Venkatesh
Abdominal Radiology 2025 (in press) https://doi.org/10.1007/s00261-024-04787-7 - Results The study group comprised of 134 patients (90 males) with 265 lesions (229 RCC-Mets and 36 PNETs). Patients with PNETs were significantly younger (62 ± 12 years vs. 67 ± 9 years, p = 0.013). Inter-observer agreement for CT/MRI features was excellent across multiple imaging variables (k = 0.86–1.00). Most PNETs were single lesions (88 vs. 63%, p = 0.008), smaller in size (14 mm vs. 23 mm, p = 0.042), more common in the body and tail (81 vs. 57%, p = 0.01), showed homogeneous contrast enhancement (64–79% vs. 39–49%, p < 0.01–0.03), less T1-hypointense (80 vs. 99%, p = 0.002) and more DWI hyperintense (71 vs. 58%, p < 0.001) compared to RCC-Mets. Conclusion PNETs are typically single, occur in distal pancreas, and enhance homogeneously compared to RCC-Mets which are often multiple, occur in the proximal pancreas, and enhance heterogeneously.
Differentiation between renal cell carcinoma metastases to the pancreas and pancreatic neuroendocrine tumors in patients with renal cell carcinoma on CT or MRI
Marie‑Joy Nduwimana . Ceylan Colak . Cem Bilgin . Blake A. Kassmeyer . Candice M. Bolan . Christine O. Menias . Sudhakar K. Venkatesh
Abdominal Radiology 2025 (in press) https://doi.org/10.1007/s00261-024-04787-7 - “Metastases to the pancreas are rare with an estimated incidence of 2–5% in clinical series. Common malignancies that metastasize to the pancreas include renal cell carcinoma (RCC), lung carcinomas, breast carcinoma, colorectal carcinoma, melanoma and soft-tissue sarcomas. RCC is the most common primary neoplasm to metastasize to the pancreas, accounting for approximately 30% of pancreatic metastases. RCC is also the most common malignancy to present with isolated pancreatic metastases. Though rare, pancreatic neuroendocrine tumors (PNETs) are the second most common primary pancreatic neoplasm with varying biologic behavior from benign to malignant. Owing to advances in diagnostic imaging, and increased utilization of CT and MRI, the incidental detection of a PNETs are increasing.”
Differentiation between renal cell carcinoma metastases to the pancreas and pancreatic neuroendocrine tumors in patients with renal cell carcinoma on CT or MRI
Marie‑Joy Nduwimana . Ceylan Colak . Cem Bilgin . Et al.
Abdominal Radiology 2025 (in press) https://doi.org/10.1007/s00261-024-04787-7 - “Our study revealed that despite the rising detection of PNETs in the general population, in patients with RCC or following nephrectomy for RCC, RCC-Mets are more prevalent than PNETs. This is as supported by the proportion of RCC-Mets to PNET cases over a period of two decades. Furthermore, our study shows that CT and MRI are useful modalities for distinguishing RCC-Mets from PNET lesions. PNETs are usually single lesions, distributed in the distal pancreas (body and tail), and homogeneously enhancing. RCC-Mets present with more multiple lesions, are distributed in the proximal region of the pancreas (head, uncinate, and neck), and show heterogeneous enhancement.”
Differentiation between renal cell carcinoma metastases to the pancreas and pancreatic neuroendocrine tumors in patients with renal cell carcinoma on CT or MRI
Marie‑Joy Nduwimana . Ceylan Colak . Cem Bilgin . Et al.
Abdominal Radiology 2025 (in press) https://doi.org/10.1007/s00261-024-04787-7 - “Lastly, several different hypervascular lesions can occur within and around pancreas that need to be differentiated from RCC-Mets and PNETs, including intrapancreatic accessory spleen, solid pseudopapillary tumor, solid serous cystadenoma, acinar cell carcinoma, hypervascular metastases, and gastrointestinal stromal tumor (GIST). Intrapancreatic accessory spleens follow the enhancement pattern of the spleen on all contrast enhanced phases and have similar signal intensity as spleen parenchyma on MRI.”
Differentiation between renal cell carcinoma metastases to the pancreas and pancreatic neuroendocrine tumors in patients with renal cell carcinoma on CT or MRI
Marie‑Joy Nduwimana . Ceylan Colak . Cem Bilgin . Et al.
Abdominal Radiology 2025 (in press) https://doi.org/10.1007/s00261-024-04787-7 - “In conclusion, there are significant differences between RCC-Mets and PNET lesions in patients with RCC on CT or MRI. PNETs are usually single, seen in the body and tail, and exhibit homogeneous enhancement. Whereas RCC-Mets to the pancreas are more often multiple, seen in the head, uncinate and neck region of the pancreas, and exhibit heterogeneous enhancement. These imaging differences may be useful for early diagnosis to triage appropriate follow-up management.”
Differentiation between renal cell carcinoma metastases to the pancreas and pancreatic neuroendocrine tumors in patients with renal cell carcinoma on CT or MRI
Marie‑Joy Nduwimana . Ceylan Colak . Cem Bilgin . Et al.
Abdominal Radiology 2025 (in press) https://doi.org/10.1007/s00261-024-04787-7
- "Metastases to the pancreas are most commonly from cancers of the kidney, lung, breast and colorectal, and from melanoma. Overall, 15–44% of pancreatic metastases have a diffuse morphological pattern. The appearance of pancreatic metastases can be similar to primary PDAC on MDCT. Pancreatic metastases often show peripheral or homogeneous (less common) enhancement; while PDACs are generally hypoattenuating lesions.”
Pitfalls in the MDCT of pancreatic cancer: strategies for minimizing errors.
Abdom Radiol 45, 457–478 (2020).
Haj-Mirzaian A, Kawamoto S, Zaheer A, Hruban RH, Fishman EK, Chu LC. - Errors in the Diagnosis of Pancreatic Cancer
- Poor CT scan acquisition protocol (poor injection, non-contrast CT, poor timing of acquisition)
- Poor CT scan parameters (thick sections, single phase acquisition, poor timing of acquisition)
- Metastases to the Pancreas: Facts
- Primary tumors
- Melanoma
- Lung carcinoma
- Breast cancer
- Renal cell carcinoma
- Renal cell carcinoma metastatic to the pancreas: Facts
- Occurs in 1-3% of cases
- Lesion may occur 20 years after the primary tumor was resected
- Usually hypervascular on CT and may only be seen in arterial phase of acquisition
- “Secondary neoplasms involving
the pancreas are increasingly recognized owing to widespread use of high-resolution imaging surveillance; however, they are still less common than primary pancreatic neoplasms, accounting for approximately 2% of all pancreatic neo- plasms. The pancreas is rarely the sole site for metastases. Secondary involvement of the pancreas can be associated with direct invasion (5%), hematogenous spread (75%), or systemic disease like lymphoma.”
Nonepithelial Neoplasms of the Pancreas, Part 2: Malignant Tumors and Tumors of Uncertain Malignant Potential Maria A. Manning et al. RadioGraphics 2018; 38 (in press) - “The most common malignancies to spread to the pancreas via direct extension are carcinomas of the gastrointestinal tract, including gastric, duodenal, ampullary, gallbladder, and transverse colonic. Hematogenous or lymphatic spread
can occur, most likely from bronchogenic carcinoma, breast carcinoma, melanomas, colorectal carcinoma, and renal cell carcinoma. As described in the preceding sections, lymphomatous and plasma cell neoplastic involvement of the pancreas is most commonly associated with systemic or widespread disease.”
Nonepithelial Neoplasms of the Pancreas, Part 2: Malignant Tumors and Tumors of Uncertain Malignant Potential Maria A. Manning et al. RadioGraphics 2018; 38 (in press) - “The differential diagnosis for hyperenhancing pancreatic neoplasms includes primary neuroendocrine tumors and metastases originating from renal cell carcinoma and melanoma. In addition,
metastatic tumors are less commonly associated with regional vascular invasion, significant pancreatic ductal dilatation, or peripancreatic lymphadenopathy.”
Nonepithelial Neoplasms of the Pancreas, Part 2: Malignant Tumors and Tumors of Uncertain Malignant Potential Maria A. Manning et al. RadioGraphics 2018; 38 (in press)
- Vascular Pancreatic Tumors
• Neuroendocrine tumor
• Serous cystadenoma
• Metastases to the pancreas (RCC)
• SPEN tumor
- “Metastatic lesions to the pancreas are uncommon and account for fewer than 5% of all pancreatic malignancies.Primary tumors of the kidney, thyroid, lung, and breast, as well as melanoma have been reported to metastasize to the pancreatic parenchyma. It is important to note that because these metastatic lesions can invade the ductal epithelium, they may produce ductal dilatation and mimic pancreatic adenocarcinoma. Metastases from renal cell carcinoma (RCC) may be found at the time of primary tumor diagnosis or, more frequently, during follow-up after surgery, and though these lesions can be solitary, they have been reported to be multiple in 20% to 45 % of patients. RCC is the most common primary tumor leading to solitary pancreatic metastases.These lesions are usually round or ovoid masses, well-delineated, and show brisk enhancement in the pancreatic late arterial phase and washout on delayed phase images. Based on enhancement alone, it can be difficult to differentiate these metastatic lesions from hypervascular neuroendocrine tumors of the pancreas.”
Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation Price M, Patino M, Sahani D Radiol Clin N Am 54 (2016) 55–70 - “RCC is the most common primary tumor leading to solitary pancreatic metastases.These lesions are usually round or ovoid masses, well-delineated, and show brisk enhancement in the pancreatic late arterial phase and washout on delayed phase images. Based on enhancement alone, it can be difficult to differentiate these metastatic lesions from hypervascular neuroendocrine tumors of the pancreas.”
Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation Price M, Patino M, Sahani D Radiol Clin N Am 54 (2016) 55–70
- “The most common primary tumors metastasized to the pancreas were renal cell carcinomas (RCC) (n = 17), gastric cancers (n = 7), and colorectal cancers (n = 5). Mean survival was significantly different between RCC (106.7 months) and non-RCC (25.1 months) metastases (P < 0.001).”
MDCT findings of pancreatic metastases according to primary tumors.
Choi TW et al.
Abdom Imaging. 2014 Nov 27. [Epub ahead of print] - “On MDCT, pancreatic metastases from RCC were frequently multifocal, located at the center of the pancreas, usually homogeneous and well-defined with early wash-in and persistent enhancement; non-RCC metastases tended to be solitary, located off-center (P < 0.05), and appeared as heterogeneous, ill-defined nodules with persistent low attenuation (P < 0.05).”
MDCT findings of pancreatic metastases according to primary tumors.
Choi TW et al.
Abdom Imaging. 2014 Nov 27. [Epub ahead of print] - “Pancreatic metastases are rare and account for only 2%–5% of all pancreatic malignancies . Nevertheless, the pancreas is occasionally a favored site for metastases in patients with advanced neoplastic disease, especially renal, lung, and breast carcinomas. Computed tomography (CT) plays a pivotal role in characterizing these tumors. Given significant differences in prognosis and treatment, it is crucial to differentiate primary and secondary pancreatic lesions.”
Metastatic disease to the pancreas: pathologic spectrum and CT patterns
Ahmed S, Johnson PT, Hruban R, Fishman EK
Abdom Imaging (2013) 38:144–153 - Metastases to the Pancreas: Sites of Origin
- Renal cell carcinoma (70.5%)
- Breast (6.8%)
- Lung (5.9%)
- Colorectal (5.5%)
- Melanoma (2.7%) - Metastases to the Pancreas: Clinical Presentation
- Asymptomatic (50-83%) and often incidental finding on imaging study
- Abdominal pain, GI bleeding, weight loss is presentation in (17-50% of cases) - Metastases to the Pancreas: CT Appearance
- Solitary (50-73% of cases)
- Multiple (10% of cases)
- Diffusely infiltrative (15%-44%) - Metastases to the Pancreas: Facts
- CT appearance ranges from round/ovoid and well marginated to homogeneous and heterogenous
- average tumor diameter of 3.9 cm
- Diffuse infiltration causes generalized enlargement of the organ and is more typical of breast and small-cell lung carcinomas - Metastases to the Pancreas: Pitfalls
Metastases may look similar to
- Pancreatic adenocarcinoma
- Non hyperfunctioning PNET
- pancreatitis
- Metastases to the Pancreas
- Only account for 2 – 4% of pancreatic masses
- Most common primary malignancy is RCC
- Can metastasize to the pancreas years after initial presentation
- Indistinguishable from NET based on imaging alone - Intrapancreatic Splenule
- 2nd most common location for accessory spleens is in the tail of the pancreas
- Easily confused for NET
- Should never be > 3 cm medial from the pancreatic tail
- Should have identical enhancement to spleen on all phases
- Technetium-99m sulfur colloid or heat denatured RBC scans if uncertain - Mimics of Pancreatic NET
- Make sure you don’t misdiagnose a splenule as a NET!
- Otherwise, nothing wrong with diagnosing these other mimics as NET in your dictations
- All of these are treated with the same surgical procedure
- Accurate preoperative diagnosis doesn’t change management
- Metastases to the Pancreas: CT Findings
- Renal cell carcinoma and lung cancer are the most common sites of origin
- Usually hypervascular mass for RCC and hypovascular mass for lung cancer
- Mass is usually well defined
- Duct dilatation is unusual
- Often multiple
- Renal Cell Carcinoma Metastatic to the Pancreas: Facts
-Usually hypervascular metastases
-Multiple lesions are common and may be seen in half the cases
-Occurs with a median interval of 6.5 to 12 years from original diagnosis. Longest interval from original diagnosis is 32.7 years
-May or may be associated with other sites of disease - Pancreatic Metastases vs Primary Adenocarcinoma: CT Findings
-Most metastases have some enhancement compared to adenocarcinoma which is typically hypodense
-Vascular invasion usually less common with metastases
-Most cases of metastases are silent asymptomatic lesions - CT Appearance of Pancreatic Metastases
-Solitary, well defined tumor (80%)
-Multiple lesions in the pancreatic gland (15%)
-Diffuse tumor infiltration (5%) - “ This pictorial essay illustrates the imaging appearances of a wide variety of metastases to the pancreas as seen on computed tomography (CT), magnetic resonance imaging and positron emission tomography/CT. Key clinical and radiologic features (lesion distribution, non-contrast imaging appearance, enhancement pattern and pattern of spread) that may aid in differentiation of primary from solitary secondary pancreatic malignancies are discussed.”
Imaging features of hematogenous metastases to the pancreas: pictorial essay
Tan CH et al.
Cancer Imaging 2011 March 1;11:9-15 - “ In 22 patients, a total of 29 metastasis were found on CT and MRI. These metastasis originated from renal cell carcinomas (22/29), colorectal carcinoma (3/29), and other malignancies (4/29). The metastasis differed not in size or location, but in their contrast enhancement characteristics.”
Metastasis to the Pancreas: Characterization by Morphology and Contrast Enhancement Features on CT and MRI
Palmowski M et al.
Pancreatology 2008;8:199-203 - Metastases to the Pancreas: Organ of Origin
-Renal cell carcinoma
-Lung cancer
-Breast cancer
-Colorectal cancer
-Malignant melanoma
-Leiomyosarcoma - Pancreatic Metastases: Facts
-Reported incidence of 1.6% -11% in autopsy series of patient with advanced malignancy
-In clinical series make up less than 5% of all pancreatic malignancies
-The diagnosis of metastases to the pancreas has important clinical implications compared to a primary pancreatic tumor from a treatment and survival prospective
-Metastases to the pancreas can be detected at initial staging or on follow-up studies - “ In difficult cases, at PET/CT the presence of diffuse uptake of FDG by the pancreas or concomitant extrapancreatic uptake by the salivary glands can be used to aid in differention of autoimmune pancreatitis and pancreatic cancer.”
Utility of 18F-FDG PET/CT for Differentiation of Autoimmune Pancreatitis with Atypical Pancreatic Imaging Findings from Pancreatic Cancer
Lee TY et al.
AJR 2009; 193:343-348 - “ The enhancement patterns of the metastatic deposits and the normal pancreas differed. Thirty-four lesions ranging in size from 6 to 110 mm were identified. All metastases showed rapid enhancement during the early (arterial and portal) phases, resulting in differential attenuations (compared with normal pancreatic parenchyma) of approximately 50-100 H. The differential attenuations were approximately 5-45 H on delayed-phase scans, resulting in poorer conspicuity of the lesions.”
- “The pancreas may be the presenting and perhaps sole locus for metastasis, typically years after treatment for certain extrapancreatic malignant neoplasms. Recognition and surgical treatment can provide worthwhile palliation and long-term survival.”
Metastases to the Pancreas and Their Surgical Extirpation
Z’graggen K, Warshaw AL et al.
Arch Surg 1008; 133:413-418 - “ The enhancement patterns of the metastatic deposits and the normal pancreas differed. Thirty-four lesions ranging in size from 6 to 110 mm were identified. All metastases showed rapid enhancement during the early (arterial and portal) phases, resulting in differential attenuations (compared with normal pancreatic parenchyma) of approximately 50-100 H.”
Metastases to the pancreas from renal cell carcinoma: findings on three-phase contrast enhanced helical CT
Ng CS et al
AJR 172, 1555-1559, 1999 - “Diagnostic radiologists performing body CT examinations on oncology patients will encounter pancreatic metastases in their practices. The diagnosis requires knowledge of the patient's primary neoplasm and familiarity with the spectrum of CT appearances we have illustrated and described. At times, pancreatic metastases may mimic primary pancreatic ductal carcinoma, islet cell tumors, and pancreatitis.”
Pancreatic Parenchymal Metastases: Observations on Helical CT
Scatarige JC, Horton KM, Sheth S, Fishman EK
AJR 2001; 176:695-699 - “Diagnostic radiologists performing body CT examinations on oncology patients will encounter pancreatic metastases in their practices. The diagnosis requires knowledge of the patient's primary neoplasm and familiarity with the spectrum of CT appearances we have illustrated and described. At times, pancreatic metastases may mimic primary pancreatic ductal carcinoma, islet cell tumors, and pancreatitis. Rarely, the metastases may be discovered before the primary site is known.”
Pancreatic Parenchymal Metastases: Observations on Helical CT
Scatarige JC, Horton KM, Sheth S, Fishman EK
AJR 2001; 176:695-699 - “ Disparity in prognosis and management between primary and secondary pancreatic tumors makes recognition of metastases to the pancreas on CT and MRI an important goal. Three different patterns of secondary pancreatic tumors may be seen; localized, multifocal, or diffuse enlargement.”
Metastases to the Pancreas
Merkle EM et al.
British J Radiol 71(1998), 1208-1214 - Metastatic Disease to the Pancreas: CT Findings
-Solitary mass most common
-Most commonly hypovascular similar to pancreatic adenocarcinoma
-Vascular metastases typical in renal cell carcinoma
-CBD or pancreatic duct obstruction may occur - Metastatic Disease to the Pancreas: Management
-Surgery in select cases
-Chemotherapy and radiation therapy may be used
-Mean survival is under 9 months - Metastatic Disease to the Pancreas: Presentation
-Incidental finding during staging/restaging of a known tumor
-Presentation with symptoms including abdominal pain, nausea, weight loss, GI bleeding or obstruction
-May present like a primary pancreatic adenocarcinoma
-Usually presents 1-3 years after initial diagnosis but may present 10-15 years later (i.e. Renal Cell Carcinoma) - Metastatic Disease to the Pancreas: Facts
May be seen in 3-12% of patients with advanced malignancy at autopsy
Most frequent site of metastases are;
-Lung cancer
-Breast cancer
-Renal cancer
-GI tract cancer
-Thyroid cancer
-Melanoma
-Hepatoma