About 90 percent of people who are diagnosed with malignant mesothelioma have chest pain or shortness of breath as the first symptoms of the disease. Chest pain is caused chiefly by the spread of the malignancy itself, which in turn causes irritation of nerve cells in nearby tissues. Less severe chest discomfort and shortness of breath generally are caused by pleural effusion (collection of fluid in the chest), not by mesothelioma itself. People with mesothelioma that originates in the peritoneum (abdominal lining) can have abdominal pain and swelling resulting from an accumulation of fluid in the abdominal cavity. Other possible symptoms include cough, fatigue and unexplained weight loss.