Mesothelial cyst of the pancreas.

Cystic lesions of the pancreas are increasingly identified because of advances in imaging techniques. The cystic lesions are of different types and are classified as neoplastic, nonneoplastic, and developmental types. Identification of the nature of these cystic lesions is very important because the course and treatment of disparate types of cysts are different. Here, we describe, for the first time, mesothelial cyst involving the pancreas in a 36-year-old man. Distal pancreatectomy showed a 3-cm unilocular cyst containing clear fluid. The cyst was lined by flat to cuboidal epithelium surrounded by fibrous tissue. The lining epithelial cells were positive for vimentin, thrombomodulin, cytokeratin 5/6, and calretinin, thus confirming the mesothelial nature of the cells.