Mediastinal teratoma mimicking massive pleural effusion.

Immature mediastinal teratoma is very rare, found in only 1% of all mediastinal teratomas. Raised serum alpha feto-protein acts as important surrogate marker for both diagnosis and follow up in such cases. Surgery and adjuvant chemotherapy are keys in the management, especially in patients older than 15 years of age. We present a 14-year-boy presenting clinico-radiologically as left sided massive pleural effusion. Raised serum marker as well as excision biopsy of the mediastinal mass following thoracotomy were indicative of a diagnosis of immature teratoma.