RESUMO
Florid vascular proliferation in teratoma is rare morphological presentation. We present a case of mediastinal germ cell tumor masquerading as a vascular neoplasm in a 14-year-old male who presented with right hemithoracic mass. The initial histopathology of resected mass was suggestive of vascular neoplasm. Fine needle aspiration cytology (FNAC) of right axillary mass with immunohistochemistry on cell block was consistent with metastatic mixed germ cell tumor. Repeat extensive sectioning of the resected mediastinal mass showed focal viable tumor with mainly teratomatous component. Further enquiry into the history revealed patient having received prior chemotherapy; this he received in another hospital before being admitted to our hospital for surgical resection of the mass. The florid vascular proliferation may represent postchemotherapy change or a rare component of germ cell tumor possibly resistant to preoperative chemotherapy.