Pancreatic Metastases and Lymphoma

Published on 19/07/2015 by admin

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Last modified 19/07/2015

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 Can be solitary (73%),  multiple (10%), or diffusely infiltrative (15%)

image Enhancement pattern mimics primary tumor

– Hypervascular: Most commonly renal cell cancer (RCC)
– Hypovascular: Lung, breast, colon, melanoma
image Concomitant intraabdominal metastases in > 60%, usually with widespread metastatic disease
• Pancreatic lymphoma

image Homogeneous soft tissue mass with little enhancement
image Diffuse enlargement of pancreas with infiltrating tumor (± peripancreatic fat involvement) may mimic acute pancreatitis
image Almost always associated lymphadenopathy or other sites of lymphomatous involvement
image Tumor classically encases peripancreatic vessels without narrowing or occlusion
image No dilatation of pancreatic duct or biliary tree

TOP DIFFERENTIAL DIAGNOSES

• Pancreatic ductal carcinoma

image Usually focal hypodense mass that obstructs main pancreatic duct resulting in upstream ductal dilatation
image Encases and narrows peripancreatic vessels
• Pancreatic islet cell tumors

image Usually hypervascular lesions which are indistinguishable from RCC metastases without clinical history

CLINICAL ISSUES

• Prognosis of metastases to pancreas poor, although isolated metastases to pancreas may be amenable to resection (especially RCC)

image RCC metastases to pancreas may occur 5-10 years after primary tumor resection
• Prognosis for primary pancreatic lymphoma is poor, with 30% cure rate after treatment
image
(Left) Axial CECT shows a hypodense mass image in the pancreatic tail due to metastatic sarcoma. Metastases from lung, breast, colon, or melanoma could have a similar appearance.

image
(Right) Coronal MIP reconstruction of an arterial phase CECT demonstrates an avidly enhancing pancreatic mass image in a patient with a history of prior nephrectomy for renal cell carcinoma (RCC), a characteristic appearance for an RCC metastasis. Based on appearance alone, this mass is indistinguishable from a neuroendocrine tumor.
image
(Left) Axial T1WI C+ MR shows an enhancing RCC metastasis image in the pancreatic head. The pancreatic duct image is mildly dilated upstream. Note the posterior position of the pancreatic tail as a result of a prior left nephrectomy for RCC several years prior to this scan.

image
(Right) Axial CECT shows diffuse infiltration of the pancreas and invasion of the spleen image by non-Hodgkin lymphoma. Also note the associated peripancreatic lymphadenopathy image.

IMAGING

General Features

• Best diagnostic clue

image Mass(es) in pancreas, usually without pancreatic or biliary ductal obstruction

CT Findings

• Pancreatic metastases

image May be solitary (73%), multiple (10%), or diffusely infiltrative (15%)
image Enhancement pattern is variable, but typically mimics primary tumor

– Hypervascular: Most often renal cell cancer (RCC)
– Hypovascular: Lung, breast, melanoma, colon
image Concomitant intraabdominal metastases in 60-95%, usually with widespread metastatic disease

– Liver, nodes, adrenal (each ∼ 30%)
image Dilatation of pancreatic duct or bile ducts less common than pancreatic adenocarcinoma (40%)
image Encasement or narrowing of peripancreatic vasculature is unusual
• Pancreatic lymphoma

image Most often presents as discrete homogeneous soft tissue mass with little enhancement
image May rarely present as diffuse enlargement of pancreas with infiltrating tumor ± peripancreatic fat involvement

– Infiltrating tumor may mimic acute pancreatitis
image Almost always associated with lymphadenopathy (especially peripancreatic) and other sites of lymphomatous involvement
image Tumor classically encases peripancreatic vasculature without narrowing or occlusion
image No dilatation of pancreatic duct or biliary tree
image 

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