Notes: Peritoneal mesotheliomas make up only 5-10% of all malignant mesotheliomas. The vast majority (90-95%) of mesotheliomas involve the pleural cavity. Most cases occur in adults (>40 yrs.) with a male predominance. About 50% of patients have history of heavy asbestos exposure. Even though the Federal exposure limits were placed in the US in 1972, the number of cases continues to increase due to the long latency period (average 15 yrs. or greater). Other risk factors for mesothelioma include exposure to Thorotrast and repeated mesothelial irritation. The presenting features include recurrent bouts of ascites, abdominal cramps, and partial bowel obstruction. Some cases present with distant lymph node or soft tissue metastasis. Here is an excellent paper on mesotheliomas: Husain AN et al. Guidelines for Pathologic Diagnosis of Malignant Mesothelioma: 2012 Update of the Consensus Statement from the International Mesothelioma Interest Group. Arch Pathol Lab Med. 2013;137:647-667.