Mesothelioma usually affects older men in their 50s, 60s, and 70s with a 25- to 40-year latency period between occupational asbestos exposure and the development of the tumor. The duration of symptoms will vary from 2 weeks to 2 years, with most series having a median time to diagnosis from symptoms of 2 to 3 months. The right side is affected more than the left side (60% vs 40%) most likely due to its greater volume.

Dyspnea will be present in 50% to 70% of the cases and, indeed, 80% of the patients will present with dyspnea and effusion. In 95% of patients with malignant pleural mesothelioma, a pleural effusion will be documented at some time in the course of the disease.

Nonspecific laboratory findings seen in mesothelioma patients include hypergammaglobulinemia, eosinophilia, and/or anemia of chronic disease. The most striking laboratory abnormality is thrombocytosis (platelet count greater than 400,000), which is seen in 60% to 90% of patients, and approximately 15% of patients will have platelet counts greater than 1,000,000. At present, validated serum markers that are both sensitive and specific for mesothelioma do not exist.

A large, unexplained pleural effusion and minimal or moderate evidence of pleural thickening demands immediate workup, which includes thoracentesis and pleural biopsy or thoracoscopy. Multiple closed pleural biopsies can be performed to avoid sampling error with the Abrams or Cope needle, and this will be able to aid in the diagnosis in 30% to 50% of the cases.

Patients who develop a large effusion and who have negative studies on thoracentesis and pleural biopsy or who recur with effusion after initial thoracentesis should have a video-assisted thoracoscopy. Thoracoscopic examination allows for targeted biopsies, which can then be analyzed with the proper pathologic markers, as well as to determine whether the lung will expand. Thoracoscopy can estimate the amount of disease on the diaphragm, pericardium, chest wall, and nodes. A chest wall mass from seeding of the biopsy site or surgical scar is an uncommon complication (approximately 10%).

Open biopsy (using an incision that can be incorporated into the definitive incision if a major resection is entertained after diagnosis) is required if there is no free pleural space due to previous treatment of pleural effusion and the bulk of the disease in the hemithorax is solid.

With the diagnosis of mesothelioma now finalized, it is important to define the extent of disease, the patient’s performance status, and his suitability for a multimodality approach using surgery and chemotherapy and/or radiation therapy. Before proceeding with these tests, a discussion with the patient must define his options. The patient is informed that the median survival of patients who select supportive care only for mesothelioma ranges widely from 4 to 13 months. Patients who elect for only chemotherapy will have a median survival of approximately 12 months even with the newest combination of pemetrexed and cisplatin, which has a 41% response rate. Patients who are eligible for multimodality approaches involving a cytoreduction of their disease by pleurectomy decortication or extrapleural pneumonectomy will have median survivals that approach 24 months, depending upon their postoperative pathologic staging status.