Use of platinum-based chemotherapy and pembrolizumab to treat squamous cell carcinoma arising in a mature teratoma of the ovary in a pre-menopausal woman with negative response: A case report.

Squamous cell carcinoma of the ovary (SCC) is a rare and aggressive disease and optimal treatment is unknown. Here we report the case of a 29- year-old woman who presented with abdominal pain and was ultimately found to have a multi-septate, gas containing pelvic mass with mixed fat, soft tissue, and calcified components concerning for a ruptured teratoma with fistulization to the distal ileum and cecum on imaging. Operative findings included a 20 cm pelvic mass arising from the right ovary with frank invasion into the ileum and cecum and dense adhesion to the anterior abdominal wall on surgical exploration. Pathologic specimens were remarkable for stage IIIC SCC of the ovary arising in a mature teratoma, with a tumor proportion score of 40%. She progressed on first line treatment with cisplatin, paclitaxel and pembrolizumab as well as second line treatment with gemcitabine and vinorelbine. She died nine months after her initial diagnosis.