Embryonal rhabdomyosarcoma arising from a mediastinal teratoma: an unusual case report.

We report an unusual case of 9.5-cm-sized embryonal rhabdomyosarcoma arose from a mediastinal mature teratoma in a 46-yr-old man. A man presented with chest trauma as a result of an accident at 10 September 2011. On chest X-ray, an anterior mediastinal mass was detected. To obtain further information, chest computed tomography (CT) with contrast enhancement was performed, revealing an anterior mediastinal mass. Complete surgical excision was performed and entire specimen was evaluated. Pathologic diagnosis was embryonal rhabdomyosarcoma arising in mature cystic teratoma. After surgical excision, two cycles of dactinomycin-based chemotherapy were performed. Lung metastasis was detected on follow up CT in September 2012, and wedge resection was performed. Pathological finding of the lung lesion showed same feature with that of primary rhabdomyosarcoma.