Teratocarcinosarcoma arising in dysgenic gonads: an unusual location for a rare tumor

Teratocarcinosarcoma (TCS) is a rare, mixed malignant tumor comprising carcinomatous, sarcomatous, and immature neuroepithelial components. While TCS most commonly affects the sinonasal tract, its occurrence within the genital tract is exceptionally uncommon. To our knowledge, there are no published reports of TCS arising in patients with ambiguous genitalia. We describe a 29-year-old phenotypic male with ambiguous genitalia who presented with intestinal obstruction due to a large abdominopelvic mass. Intraoperative findings included a rudimentary uterus, fallopian tube, and ovary, all resected en bloc with the tumor. Histopathological examination revealed adenocarcinoma with mucinous and squamous differentiation, intimately admixed with sarcomatous areas, immature neuroepithelium, and cartilage. Distinct morphological features and PAX8 positivity were instrumental in confirming Müllerian origin and differentiating the tumor from teratoma with somatic-type malignancy and other germ cell tumors. The contralateral ovary exhibited fibroblastic interstitium, lacking follicles and tubules. These findings support the hypothesis that TCS may originate from arrested development of primitive embryonic tissues, which represents one of the proposed histogenetic mechanisms. The identification of an actionable PIK3CA mutation in this case highlights a potential therapeutic target, given the poor response to conventional platinum-based chemotherapy.