Malignant Pleural Mesothelioma with Marked Lymphatic Involvement: A Report of Two Autopsy Cases

We herein report two cases of malignant pleural mesothelioma with marked lymphangiosis. The patients included a 68-year-old man and a 67-year-old man who both had a history of exposure to asbestos. Computed tomography (CT) on admission showed pleural effusion with pleural thickening. In both cases, a histopathological examination of the pleura confirmed the diagnosis of epithelioid malignant mesothelioma. They received chemotherapy, but the treatment was only palliative. The chest CT assessments during admission revealed marked pleural effusion and mediastinal lymphadenopathy. CT also showed a consolidative mass with bronchovascular bundle and septal thickening in the lungs suggesting pulmonary parenchymal involvement and the lymphangitic spread of the tumor. These CT findings mimicked lung cancer with pleuritis and lymphangitic carcinomatosis. Autopsy was performed in both cases. Macroscopically, the tumor cells infiltrated the lung with the marked lymphatic spread of the tumor. Microscopy also revealed that the tumor had invaded the pulmonary parenchyma with the marked lymphatic spread of the tumor. Although this growth pattern is unusual, malignant pleural mesothelioma should be considered as the differential diagnosis, especially in patients with pleural lesions.