[Case of malignant lymphoma arising from the posterior mediastinum, with pleural effusion].

We report a rare case of malignant lymphoma arising from the posterior mediastinum with bilateral pleural effusion. A 71-year-old man was admitted to our hospital for evaluation of a posterior mediastinal tumor and bilateral pleural effusion revealed on a chest CT scan. Because no tumor tissue could be obtained by fiberbronchoscopy, video-assisted thoracoscopic surgery was performed. The tumor sample was composed of large, atypical lymphocytes positive for CD20 on immunohistochemical analysis. A diagnosis of diffuse large B cell lymphoma was made from the typical histological features. The patient was treated with combination chemotherapy (CHOP) and rituximab and improved dramatically.