ABSTRACT
Extra-gonadal malignant transformation of teratoma is rare and there are only a few reports available citing malignancy arising in the non-germ cell components. We hereby report a case of a 35-year-old female, who presented with lower backache with a radiologically identifi able mass lesion in the pre-sacral region. Clinical and radiological fi ndings suggested the possibility of a cystic teratoma. Histopathological examination and relevant immunohistochemical tests detected a mature cystic teratoma with features of a grade 2 neuroendocrine tumor in it. Like the index case, most of the previously reported cases of teratoma with malignant transformation of the somatic components were found in extra-gonadal site. This case is being reported to emphasize that any extra-gonadal mass in reproductive age group, even if it appears radiologically and per-operatively benign, must be subjected to histopathological examination to rule out possibility of malignant transformation of the germ cell or non-germ cell components.