Epithelioid Trophoblastic Tumour: A Case with Genetic Linkage to a Child Born over Seventeen Years Prior, Successfully Treated with Surgery and Pembrolizumab

Epithelioid trophoblastic tumours are rare neoplasms showing differentiation towards the chorion leave-type intermediate cytotrophoblast, with only a handful of cases being reported in the literature. These tumours are slow-growing and are typically confined to the uterus for extended periods of time. While the pathogenesis is unclear, they are thought to arise from a remnant intermediate trophoblast originating from prior normal pregnancies or, less frequently, gestational trophoblastic tumours. A protracted time period between the gestational event and tumour development is typical. This case describes a 49-year-old previously healthy female who presented with a completely asymptomatic uterine mass, discovered incidentally during a routine gynaecological assessment. The pathological analysis of the hysterectomy specimen confirmed an epithelioid trophoblastic tumour, involving the uterus and cervix. This is a rare gynaecological tumour. A comparative short tandem repeat analysis revealed genetic similarities to a previous healthy gestation seventeen years prior. She was successful treated with adjuvant pembrolizumab, with no evidence of disease recurrence to date.