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. The symptoms of peritoneal msothelioma could be vague, such as abdominal discomfort, weight loss, constipation, or diarrhoea. A mesothelioma specialist can