Malignant pleural mesothelioma (MPM) is an asbestos-related tumor arising in the pleural cavity. Symptoms reflect extension of disease and include shortness of breath and chest pain. Unexplained pleural effusion and pleural pain in patients exposed to asbestos should raise the suspicion of MPM. The most common radiologic presentation is ipsilateral pleural effusion with or without pleural thickening or a mass. Thoracoscopic biopsy remains the most appropriate procedure for definitive diagnosis of mesothelioma. Despite advancement in diagnostic procedures and biomolecular research, this tumor nevertheless has poor prognosis. Mesothelioma remains a diagnostic and therapeutic challenge and is likely to remain one in the years to come.

Here we present the first reported case of steroid treatment responsive pleural effusion in a 72 year-old-male that initially was misdiagnosed as rheumatoid related effusion. However, Pleuroscopy with biopsy revealed mesothelioma.