Peritoneal Mesothelioma Not Caused by Asbestos Malignant peritoneal mesothelioma forms in the abdomen's lining. It is less frequent than the pleural variant and more women are affected than men. Symptoms of peritoneal msothelioma can be vague, like abdominal discomfort constipation, weight loss or diarrhoea. A mesothelioma specialist can help with