Lymphoepithelial cyst and epidermoid cyst of the accessory spleen in the pancreas

Abstract

We report here two rare cystic lesions, a lymphoepithelial cyst (LEC) and an epidermoid cyst of the accessory spleen (ECAS) occurring in the pancreas. Histologically, the LEC was lined by stratified squamous epithelium and surrounded by a layer of lymphoid tissue with germinal centers. The ECAS showed similar histologic features with scattered lymphoid tissue, but splenic pulp tissue was present in the wall. In both cysts, some small pancreatic islets and ducts were seen in the fibrous tissue surrounding the lymphoid layer or the splenic pulp, respectively. The lining epithelia of the LEC and the ECAS, as well as those of retention cysts of the pancreas and epidermoid cysts of the spleen used for comparison, were similarly positive with AE1/3, CAM5.2, CK7, CK13, and carcinoembryonic antigen. CA19-9 was also detected in the epithelial cells of the LEC, the ECAS, and the retention cyst of the pancreas, but not in those of the splenic epidermoid or branchial cleft cysts used for comparison. These findings indicate that LECs and ECASs might develop from the pancreatic ducts protruding into a lymph node or accessory spleen located in the pancreas, respectively. Some of both cysts might cause elevated levels of serum carcinoembryonic antigen and/or CA19-9 and should be distinguished from malignant cystic tumors.