[Intrathoracic neurofibroma originating in the left vagus nerve].

A 20-year-old man was admitted because of an abnormal mass shadow on chest X-ray film. Computed tomography (CT) and magnetic resonance imaging (MRI) disclosed a mass lesion in the superior portion of the left mediastinum. CT scans showed a well-defined mass with low density. Axial MRI rendered the mass lesion with intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. The preoperative diagnosis was bronchogenic cyst. Video-assisted thoracic surgery revealed that the tumor originated in the truncus of the left vagus nerve. The resected tumor was 90 x 24 x 18 mm in size. The postoperative course was uneventful and hoarseness did not develop. The pathologic diagnosis was benign mediastinal neurofibroma without von Recklinghausen's disease. Such cases are extremely rare in the Japanese literature.