Lymphoepithelial cyst of the pancreas associated with elevated CA 19-9 levels.

An extremely rare case of a lymphoepithelial cyst associated with persistent elevation of serum carbohydrate antigen (CA) 19-9 levels is described. A 72-year-old man was incidentally found to have a cystic tumor in the uncus of the pancreas and to have a high serum CA 19-9 level. At 2-year follow up, the tumor size had gradually increased and the high CA 19-9 level persisted. Because the malignant potential of the tumor could not be ruled out, a laparotomy was performed. The tumor was excised from the pancreas. On pathological examination, the tumor was proven to be a lymphoepithelial cyst. After the operation, the patient's serum CA 19-9 level decreased to the normal range. Lymphoepithelial cysts of the pancreas are a rare, benign entity. They are true pancreatic cysts, characterized by a mature, keratinizing, squamous lining surrounded by lymphoid tissue. Because the treatment options and the prognosis of these entities are quite different from those of other cystic neoplasms of the pancreas, preoperative differential diagnosis is the main issue. Thus, although they are rare, lymphoepithelial cysts should be considered in the differential diagnosis of cystic tumors of the pancreas.