Multicystic, peritoneal mesothelioma: a report with electron microscopy of a case mimicking intra-abdominal cystic hygroma (lymphangioma).

A 27-year-old Caucasian female complained of persistent, poorly localized abdominal pain of several months' duration, found to be due to a multicystic diffuse lesion involving omentum, peritoneum and pelvic viscera. Three resections were required within a ten-month period for symptomatic control. The tumor showed many of the clinical, operative, gross and light microscopic features of intra-abdominal lymphagioma. Tissues removed at the third operation, however, were examined by electron microscopy, and found to consist of a myriad of small cysts and channels lined by mesothelial cells. In view of these findings, the lesion was regarded as a cystic peritoneal mesothelioma. Similarities between lymphangioma and peritoneal mesothelioma are discussed. It is suggested that electron microscopic examination of lining cells of cystic lesions which are considered grossly consistent with lymphagiomas may yield additional similar cases.