Peritoneal cystic mesothelioma: an electron microscopic and immunohistochemical study of two male patients.

The clinical, pathological, and ultrastructural features of two cases of peritoneal cystic mesothelioma occurring in men were studied. The results of immunohistochemical staining for CAM 5.2, epithelial membrane antigen, carcinoembryonic antigen, and Factor VIII related antigen are reported for the first time and compared with the staining results of two peritoneal cystic lymphangiomas. Although resembling cystic lymphangioma by light microscopy, cystic mesothelioma may have a greater tendency for local recurrence. Staining for CAM 5.2 or epithelial membrane antigen may facilitate the differentiation of these two entities.