Pediatric lynch-associated melanoma arising in ovarian teratoma: a case report

Background Mature teratomas of the ovary are a benign entity. However, rare secondary malignant transformation of germ cell components may occur and give rise to a teratoma of malignant transformation (TMT). While reports of this pathology have been described in peri- and postmenopausal patients, this represents the first case of teratoma-associated malignant melanoma in a pediatric patient with Lynch syndrome. There is a lack of consensus recommendations regarding management of this rare phenomenon. Case Presentation We present the case of a 12-year-old premenarchal female with a pelvic mass who underwent surgical resection with final pathology consistent with a melanoma in a teratoma of malignant transformation. She was subsequently diagnosed with a germline MSH6 mutation during postoperative evaluation. She received adjuvant ipilimumab and nivolumab for 3 cycles complicated by grade 3 transaminitis responding to medical therapy. An interval laparoscopic ovarian cystectomy was performed on the contralateral ovary due to concern for recurrence, which was negative. The patient remains on single agent nivolumab without evidence of detectable disease almost 18 months after initial diagnosis. Conclusion Melanoma arising from a teratoma of malignant transformation is an exceedingly rare pathological diagnosis, especially in the pediatric population. Surgical management is the mainstay of treatment with addition of systemic therapy including immunotherapy. Lynch syndrome in a pediatric patient presents additional considerations for future cancer risk and fertility. Finally, while ctDNA may have a role in the detection of recurrence and treatment planning, this remains investigational.