[Adrenal cyst with an immunohistochemical evidence of mesothelial origin. Report of a case].

A case of adrenal cyst with an immunohistochemical evidence of mesothelial origin is presented. A 73-year-old Japanese woman was referred to our hospital with a complaint of left flank pain. The diagnosis of left adrenal cyst was made based on the radiographic and hormonal examinations. The adrenal cyst was removed surgically. Histological examination revealed that the cyst was lined with either a single layer of squamous or cuboidal cells. In immunohistochemistry testing, the cells were positive for keratin and carbohydrate antigen 125, while they were negative for epithelial membrane antigen, vimentin, desmin, and factor VIII related antigen. Thus, the present case was classified as epithelial cyst of mesothelial origin.