[Sarcoidosis differentially diagnosed from mediastinal tumor by thoracoscopic biopsy]

A 46-year-old man presented with swallowing difficulty and dyspnea when in the supine position. Chest X-ray and computed tomographic (CT) films disclosed left pleural effusion and a tumor shadow extending invasively from superior to anterior mediastinum around the heart and large arteries. These observations called for a differential diagnosis from malignant lymphoma, invasive thymoma, and small cell carcinoma. Bronchofiberscopy and percutaneous tumor biopsy were performed, but the findings were inconclusive. Thoracoscopic biopsy yielded a diagnosis of sarcoidosis. No extrathoracic lesions were detected. Corticosteroid therapy (30 mg/day of prednisolone) was started. After 6 months of treatment (7.5 mg/day of prednisolone), the tumor shadow was reduced in size and the patient's swallowing difficulty and dyspnea subsided. This was a rare case of sarcoidosis extending invasively around the heart and large arteries, and that needed to be differentiated from mediastinal tumor. Thoracoscopic biopsy should be actively enlisted as a diagnostic procedure in difficult cases of this kind.