Mesothelioma is classified into four types based on where in the body it develops. Pleural mesothelioma (lining of the lungs) accounts for approximately 75% of all cases, peritoneal mesothelioma (lining of the abdomen) accounts for about 20%, and pericardial and testicular mesothelioma are extremely rare, each accounting for less than 1% of diagnoses.
Pleural Mesothelioma
Pleural mesothelioma develops in the pleura — the thin membrane that lines the lungs and chest cavity. It is the most common form, accounting for roughly 75% of all mesothelioma diagnoses. When asbestos fibers are inhaled, they can become lodged in the pleura, causing chronic inflammation and cellular changes that eventually lead to cancer, typically 20 to 50 years after initial exposure.
Symptoms include persistent chest pain, shortness of breath, chronic cough, unexplained weight loss, and pleural effusion (fluid buildup around the lungs). Treatment options include surgery (pleurectomy/decortication or extrapleural pneumonectomy), chemotherapy with pemetrexed and cisplatin, immunotherapy with nivolumab and ipilimumab, and radiation therapy. The most effective approach is multimodal treatment combining two or more of these options.
Peritoneal Mesothelioma
Peritoneal mesothelioma develops in the peritoneum — the membrane lining the abdomen. It accounts for approximately 20% of cases. Asbestos fibers can reach the peritoneum through ingestion or through the lymphatic system after inhalation.
Symptoms include abdominal pain and swelling, nausea, unexplained weight loss, bowel changes, and ascites (fluid buildup in the abdomen). The landmark treatment advance for peritoneal mesothelioma is HIPEC — hyperthermic intraperitoneal chemotherapy — where heated chemotherapy is applied directly to the abdominal cavity during surgery. HIPEC combined with cytoreductive surgery has dramatically improved outcomes, with some studies showing 5-year survival rates of 50–60% in select patients.
Pericardial Mesothelioma
Pericardial mesothelioma develops in the pericardium — the membrane surrounding the heart. It accounts for less than 1% of all mesothelioma cases. Due to its rarity and location near the heart, it is often not diagnosed until autopsy. Symptoms include chest pain, irregular heartbeat, difficulty breathing, and pericardial effusion (fluid around the heart). Treatment options are limited, though surgery may be possible in early-stage cases.
Testicular Mesothelioma
Testicular mesothelioma develops in the tunica vaginalis — the membrane lining the testes. It is the rarest form, accounting for less than 1% of cases. Despite being the rarest, it has the best overall prognosis among the four types, with a 5-year survival rate of approximately 50%. It is typically discovered during surgery for other conditions and treated with surgical removal.