Mature cystic teratoma with malignant transformation of teratomatous urothelial cells: Rare case presentation

The occurrence of malignancies in somatic elements of mature cystic teratoma of ovary is rare. The malignancies that may be encountered in dermoid cyst include squamous cell carcinoma, adenocarcinoma, adenosquamous carcinoma, melanoma, sarcoma, carcinoid, and germ cell neoplasms. The development of transitional cell carcinoma (TCC) in dermoid cyst is extremely rare with only four such cases having been reported in literature so far. Here we report the fifth case of such an occurrence in a 50-year-old postmenopausal multiparous female patient. She presented with pain and gradual swelling of abdomen for 1 month. Abdominal computed tomography revealed a solid space occupying lesion with few cystic components at right pelvis, raising the possibility of an ovarian neoplasm. The level of CA-125 was slightly raised (56∙45 U/ml). Total abdominal hysterectomy and bilateral salpingo-oopherectomy was performed. Microscopic examination showed cyst wall lined by stratified squamous epithelium. Beneath the cyst wall, a tumor mass was present, histological features of which resembled that of high-grade TCC (stage pT1aNXMX). On immunohistochemical analysis, the tumor was found to be positive for CK7 and CK20 and negative for WT-1. These results were consistent with a diagnosis of TCC arising in urothelium of mature cystic teratoma. Reporting of such extremely rare cases is important for the assessment of prognostic factors and treatment protocols.