Peritoneal mesothelioma.

Peritoneal mesothelioma is a rare neoplasm often related to previous asbestos exposure. In 14 cases the diagnosis before surgery was virtually impossible, as patients presented with vague abdominal complaints and nonspecific physical examination findings. Laboratory testing (including computed tomography) was of no added diagnostic help. Widespread peritoneal neoplastic growth was the common finding at laparotomy. The tumor was grossly indistinguishable from other types of abdominal carcinomatosis. Electron microscopy proved to be the diagnostic tool of choice. Routine histologic techniques often gave nondiagnostic results. Intraperitoneal asbestos fibers were not observed. Treatment with radiation, chemotherapy, or both produced a 50% partial response rate, but survival was not affected. Malignant ascites was effectively palliated without complication in two of three patients with peritoneovenous shunting. An unusual case occurred in which histologic material from a second-look laparotomy documented complete response to a new regimen of intraperitoneal chemotherapy.