Neuroblastoma arising from an unresected sacrococcygeal teratoma in a child.

Malignant transformation of a germ cell tumor, referring to the occurrence of somatic, nongerm cell malignancy within a germ cell tumor is a rare entity. The authors report a case of malignant transformation of an unreseceted sacrococcygeal teratoma to neuroblastoma in a 6-year-old girl and discuss this case in the light of relevant literature. This case shows that complete resection of germ cell tumor is necessary to prevent malignant transformation. In addition, when malignant transformation occurs, the treatment strategy must include surgery together with histology adapted systemic chemotherapy.