Abstract

Synovial sarcoma is uncommon malignant soft tissue tumor. This tumor occurs usually in adults and is rare in children under 15 years of age. Moreover congenital synovial sarcoma is extremely rare. Only 2 cases have been reported in the literatures. We experienced 1 month male infant who had been a egg-sized mass in right lateral malleolus since at birth. The mass was located subcutaneously and showed no direct relationship to the joint cavity or underlying bone. The mass was removed surgically. The tumor consisted of irregular firm gray to yellow mass and showed area of hemorrhage and necrosis on cut surface. Microscopically the tumor-showed biphasic pattern. The synovial nature of the tumor was confirmed by electron microscopy.