High-grade Invasive Papillary Urothelial Carcinoma Arising in a Mature Cystic Teratoma of the Ovary: A Case Report, Including Its Molecular Profile, and a Literature Review.

Urothelial carcinoma arising in a mature cystic teratoma of the ovary is a rare event with only 13 cases reported thus far. In this article, we present the clinicopathologic features of one such case and a review of the literature. The patient was a 76-yr-old African American postmenopausal woman who presented with a painful abdominal mass and weight loss. The left ovarian tumor was 36 cm in greatest dimension and contained several papillary areas, the largest being 10 cm. The patient underwent a total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy and pelvic washings. Microscopically, the papillary excrescences represented an invasive, high-grade papillary urothelial carcinoma, while the cyst in the background was a mature cystic teratoma. Immunohistochemically, the urothelial carcinoma was positive for CK7, CK20, GATA-3, uroplakin II, p40, p63, and ER (20%, weak intensity), while negative for WT1 and PR; p53 expression was aberrant (nuclear overexpression). Next-generation sequencing (NGS) showed a microsatellite-stable tumor with low tumor mutational burden, and molecular alterations typically seen in urothelial carcinomas, including KRAS gain of function, ARID1A loss of function, RB1 loss of function, and two TP53 loss of function mutations. In addition, PDL1 positivity was present, representing a clinically actionable target. The tumor was FIGO stage 1A. No adjuvant therapy was given, and the patient is alive with no evidence of disease after a follow-up of 7 mo.