Secondary Tumors and Lymphoma

Abstract

Pancreatic metastases are uncommon entities [ 1 , 2 ].Metastases can occur through different ways: by direct invasion, from systemic malignancies such as lymphomas or leukemias, or by metastatic spread from a distant tumor [ 3 ].Primary pancreatic lymphoma is another rare pancreatic neoplasm that accounts for less than 1 % of all pancreatic tumors [ 4 ].Compared to primary pancreatic lymphoma, the secondary involvement of the pancreas by non-Hodgkin's lymphoma is more common and can occur in 30-40 % of patients with extranodal disease [ 5 ]. Secondary Tumors and Lymphoma Pathology MetastasesTumors that directly invade the pancreatic parenchyma generally arise from adjacent structures such as Vater's papilla, extrahepatic bile ducts, stomach, duodenum, or colon [ 6 , 7 ]. Pancreatic involvement by lymphomas and leukemias usually derives from the involvement of peripancreatic lymph nodes; overall, this condition can be seen in up to 30 % of patients with widespread disease [ 8 ].True pancreatic metastases more commonly arise from renal cell carcinoma (which are the most frequent), melanoma, and breast and lung adenocarcinoma [ 2 , 9 , 10 ]. The dissemination route to the pancreas can be either lymphatic or hematogenous; the fi rst is pretty typical for colorectal cancer, due to the unique lymphatic drainage through the mesocolon to the pancreas. In these cases, the most frequent site of implantation of metastases is the inferior portion of the pancreatic head.The exact prevalence of pancreatic metastases is not clear: the reported frequency in autoptic studies ranges between 1.6 and 5.9 % [ 2 , 11 , 12 ], while pancreatic metastases have been observed in 0.7-10.7 % of endoscopic ultrasoundguided fi ne-needle aspirations [ 10 , 12 -14 ].