[Liposarcoma originating in the neck and the mediastinum after removal of mediastinal lipoma].

A 47-year-old man, who had undergone removal of an upper mediastinal lipoma 9 years previously, was referred to our hospital for swelling of the right neck and wheezing. The chest X-ray showed enlargement of the upper mediastinum. Contrast-enhanced chest computed tomography and magnetic resonance imaging demonstrated a tumor with fatty density extended from the upper mediastinim to the right side of the neck. Two-stage tumor resection was carried out. On gross pathological examination the tumor was soft and fatty. Microscopic examination revealed well differentiated liposarcoma. Postoperative radiation therapy (50 Gy) was carried out. The patient remains free of disease 3 years after radiation therapy.