Selected case from the Arkadi M. Rywlin International Pathology Slide Seminar: benign lymphoepithelial cyst, head of pancreas.

Pancreatic lymphoepithelial cysts are more common in men, can occur anywhere in the pancreas, are sharply demarcated from surrounding tissues, and range in size from 1.2 to 17 cm. Patients are usually middle aged, presenting symptoms include abdominal pain, nausea, vomiting, and diarrhea, although many tumors are asymptomatic and are discovered incidentally on organ imaging or at autopsy. An elevated serum carbohydrate-associated antigen 19-9 may wrongly suggest a mucinous neoplasm. The diagnosis can be made preoperatively with a combination of organ imaging, fine needle aspiration biopsy, or ultrasound-guided Trucut biopsies. Cysts can be unilocular, bilocular, or multilocular, have walls up to 0.6 cm thick which are lined by squamous epithelium, occasional columnar mucinous cells, and small foci of sebaceous cells. The epithelium is surrounded by a dense rim of lymphoid tissue with scattered lymphoid follicles. Invaginations of the epithelium into the lymphoid tissue, reminiscent of a Warthin tumor, are occasionally observed. The pathogenesis is unknown. Pancreatic lymphoepithelial cysts are cured by conservative resection but if they are asymptomatic and are diagnosed before surgery, no treatment is necessary.