Pancreatic lymphoma: A cytologic diagnosis challenge

Very rarely lymphoma primarily or secondarily involves the pancreas. Involvement of the pancreatic parenchyma with lymphoma clinically may mimic pancreatic ductal adenocarcinoma (PDA) and other mass-forming pancreatic lesions. Endoscopic ultrasound fine needle aspiration (EUS-FNA) is the first step in the diagnostic pathway of managing these patients by providing a cytology specimen. Cytologically, lymphoma of pancreas can be misdiagnosed for a wide variety of pancreatic neoplastic and non-neoplastic lesions. Cytological differential diagnosis includes well-differentiated adenocarcinoma, acinar cell carcinoma, well differentiated neuroendocrine tumor, and autoimmune pancreatitis. Gastroenterologist's skills in providing adequate sample for preparing smears, cell blocks and/or performing flow cytometry, and also cytopathologist's skills in detecting atypical lymphocytic population are crucial factors. Although cytology examination has limitations to subclassify lymphoma, it plays a key role to redirect clinicians into the right patient-care pathway. In this article, we present two cases of pancreatic lymphoma with emphasis on the discriminating cytomorphological features, and we also review literatures with reports of primary pancreatic lymphoma (PPL) to better understand the characteristics of this rare lesion.