Cyst fluid cytology and chemical features in a case of lymphoepithelial cyst of the pancreas: A rare and difficult preoperative diagnosis

Most pancreatic cysts (90%) are inflammatory pseudocysts. Approximately 10% of pancreatic cysts are neoplasms, including serous cystadenomas, and muci nous tumors, some of which are malignant. Analysis of pancreatic cyst fluid obtained by percutaneous or endoscopic fine-needle aspiration is increasin gly being used for the preoperative diagnosis of pancreatic or peripancreat ic cysts. However, cyst fluid chemical and cytologic features in less commo n types of pancreatic cysts have not been reported. Lymphoepithelial cyst o f the pancreas is exceedingly rare, and only occasional individual reports have described cyst fluid findings. We report on a case of lymphoepithelial cyst of the pancreas developing in a middle-aged man. Cyst fluid aspirated under radiological guidance showed elevated levels of carcinoembryonic ant igen (CEA), CA19-9, CA 125, and amylase, and a viscosity greater than that of serum. A cell block preparation of a fine-needle aspiration showed tissu e fragments with a keratinized squamous lining and a lymphocytic infiltrate in the wall, and abundant background keratinous debris. The cytologic and biochemical findings in this case exhibit similarities to the findings repo rted in other reports, and may represent a recognizable pattern on cyst flu id analysis. Diagn. Cytopathol. 1999;21:328-330. (C) 1999 Wiley-Liss, Inc.