[Mediastinal amelanotic melanoma presenting as superior vena cava syndrome].

A 60-year-old man was admitted to the hospital with anterior chest discomfort and superior vena cava syndrome. A chest X-ray film revealed a right upper mediastinal mass. A needle biopsy was done. Anaplastic tumor cells was found after HE staining. No melanin was found and the origin of the tumor cells could not be determined. Radiation and chemotherapy caused the tumor to shrink markedly. Because the tumor had invaded the superior vena cava, only reduction surgery could be done. The patient died 6 months after admission. Amelanotic malignant melanoma was diagnosed after immunohistochemical study of the resected specimen. Mediastinal malignant melanoma has been reported very infrequently and to our knowledge this is the first report of mediastinal amelanotic malignant melanoma.