Clinico-Pathological Discordance in a Partial Hydatidiform Mole With Coexisting Live Fetus and Subsequent Aggressive Gestational Trophoblastic Neoplasia: A Case Report

Twin pregnancies with a partial hydatidiform mole and a coexisting live fetus are exceptionally rare, and progression to chemoresistant gestational trophoblastic neoplasia (GTN) is even less common. We report the case of a 28-year-old nulligravid woman with prior ovulation induction who presented with a twin pregnancy consisting of a partial hydatidiform mole and a coexisting live normal fetus. Following spontaneous abortion and uterine evacuation, histopathological examination and immunohistochemistry demonstrated p57 positivity, supporting the diagnosis of partial hydatidiform mole, and a normal placental tissue with a fetus without malformations. Despite apparently favorable pathological findings, the patient developed giant theca-lutein cysts complicated by ovarian torsion, progression to GTN, resistance to methotrexate and actinomycin-D, and subsequent pulmonary metastasis. Multi-agent chemotherapy with EMA-CO (etoposide, methotrexate, actinomycin-D, cyclophosphamide, and vincristine) achieved complete clinical and biochemical remission, with no evidence of recurrence after three years of follow-up. This case highlights that partial hydatidiform mole with a coexisting live fetus may rarely exhibit aggressive clinical behavior despite reassuring histopathological and immunohistochemical features. Careful clinical and human chorionic gonadotropin surveillance remains essential in complex molar pregnancies.