A case of mediastinal giant hemangioma was reported. The patient was a 13 years old female. She was asymptomatic, but an abnormal cardiac silhouette was pointed out in a chest X-Ray film and the patient was transferred to our hospital. At operation, a polycystic giant anterior mediastinal mass was resected, that was diagnosed as hemangioma. The tumor was 16x11x7 cm in size and weighted 694 gram. Mediastinal hemangioma is very rare. Most patients are asymptomatic. It is often found by a radiological examination. All the cases reported in Japan are histologically benign, but some malignant cases have been reported in foreign countries. So, whenever the patient is suspectecd to have a mediastiaal tumor or mediastinal hemangioma, the tumor must be resected as soon as possible.
