Epithelial splenic cysts in an intrapancreatic accessory spleen and spleen

A rare case of cysts simultaneously occurring in the intrapancreatic access ory spleen and spleen in a 49-year-old female is reported. The patient unde rwent distal pancreatomy for a cystic tumor of the pancreas, and a splenect omy. A multilocular cyst (4.3 x 2.6 cm) in an accessory spleen at the pancr eas tail, and a solitary cyst (1.2 x 0.9 cm) of the spleen were found. The cyst in the intrapancreatic accessory spleen was lined by non-keratinizing stratified squamous epithelium, and the spleen cyst by a single layer of fl at epithelium; these lining cells were positive for Alcian blue stain and p eriodic acid-Schiff reaction, and were immunohistochemically positive for c ytokeratin, HBME-1 and Sialyl-Tn. Epithelial membrane antigen, carcinoembry onic antigen and CA19-9 were positive in the accessory spleen cyst but were negative in the spleen cyst. An electron microscopic examination of the fl at epithelium of the spleen cyst revealed numerous microvilli on the surfac e, cytoplasmic microfilaments, and a number of tight junctions between adja cent cells. These features suggested that the two cysts differ in nature, a nd origin; the accessory spleen cyst may be an embryonic inclusion of the p ancreas duct while the spleen cyst may be an inclusion cyst of the mesothel ium.