Synchronous occurrence of pulmonary adenocarcinoma and pleural diffuse malignant mesothelioma.

We report a rare case of diffuse malignant pleural mesothelioma synchronous with a localized adenocarcinoma of lung in a 68-year old man with a suspicious history of asbestos exposure. Computed tomography revealed a sub-pleural mass in the lower lobe and an irregular dense area of medium lobe of right lung with thickening of pleura encasing the lung parenchyma and homolateral pleural effusion 1 cm thick. The patient underwent surgery and a right medium and lower lobectomy was performed. Upon frozen sections, intraoperative diagnosis was adenocarcinoma with a poorly differentiated component of lung infiltrating the pleura. The postoperative histological definitive diagnosis with an important contribution of immunostaining was synchronous pulmonary adenocarcinoma and pleural diffuse malignant epithelioid mesothelioma.