[Angiomyolipoma of the anterior mediastinum--a case report].

An asymptomatic 22-year-old female showed an enlarged mediastinal shadow in a chest X-ray mass screening. Computed tomogram indicated a tumor with a CT-number of 7-8 in her left anterior mediastinum, adjacent to the pericardium. With MRI the tumor showed a low signal intensity of T1 weighted images and a high signal intensity of T2 weighted images. Thoracotomy revealed that the tumor was yellow-whitish, and had a size of 7 x 7 x 1 cm. It was histologically composed of fatty tissue, smooth muscle, and vascular tissue, and was diagnosed as angiomyolipoma. Although angiomyolipomas are often found in the kidney, they are very rare in the mediastinum and difficult to diagnose by image analysis.