[Primary Pancreatic Lymphoma Coexisting with Intraductal Papillary Mucinous Neoplasm-A Case Report].

An 81-year-old woman was diagnosed with a tumor in the pancreas, detected on CT and MRI. The tumor was 12 mm in diameter and located close and in the distal side of the branch duct-type intraductal papillary mucinous neoplasm(IPMN)in the pancreas head observed for 4 years. Pancreatic ductal adenocarcinoma derived from IPMN was suspected and pylorus-preserving pancreatoduodenectomy was performed. The immunohistological diagnosis of the tumor using a resected specimen was diffuse large B cell lymphoma of the pancreas. After surgery, chemotherapy was not performed because of the patient's decision, but 2 years later, relapse of malignant lymphoma was suspected because of swelling of the bilateral adrenal glands on MRI. R-CHOP immunochemotherapy was started, but seven months later the patient died of lymphoma involving the central nervous system. Primary pancreatic lymphoma(PPL)is a rare disease representing 0.6% of extranodal lymphoma. Many cases of PPL are large, and small lesions under 2 cm in diameter are extremely rare. Furthermore, PPL associated with IPMN has never been reported. The pancreatic tumor close to the IPMN is difficult to diagnose differentially from adenocarcinoma on radiological findings. However, nonsurgical biopsy of the tumor in the pancreas is sometimes challenging if associated with IPMN.