Lymphoepithelial cyst (LEC) of the pancreas: cytomorphology and differential diagnosis on fine-needle aspiration (FNA).

Lymphoepithelial cyst (LEC) of the pancreas is an extremely rare benign entity. We describe the cytopathologic findings of such a lesion in a 49-yr-old woman who was examined for epigastric pain. A trans-esophageal ultrasound-guided fine-needle aspiration of a pancreatic mass disclosed an intimate mixture of squamous epithelial cells and small, mature lymphocytes in a background of keratinaceous debris, anucleate squames, and multinucleated histiocytes. On histopathologic examination, a subsequent resection showed a multiloculated cystic lesion with a stratified squamous epithelial lining surrounded by well-formed lymphoid tissue, suggestive of LEC. The differential diagnosis includes other pancreatic pseudocysts, dermoid cyst, mucinous cystic neoplasms, adenosquamous carcinoma, and metastatic squamous cell carcinoma.