Primary tubal choriocarcinoma with extrauterine implantation masquerading as ectopic pregnancy

Rationale: Gestational trophoblastic neoplasia, particularly choriocarcinoma, is a rare but aggressive malignancy arising from trophoblastic tissue. Primary tubal choriocarcinoma is exceptionally uncommon and often presents a diagnostic challenge owing to its similarity to ectopic pregnancy. Patient concerns: A 29-year-old woman presented with irregular menses. Clinical suspicion of ectopic pregnancy was raised due to extremely high β-human chorionic gonadotropin levels and suggestive ultrasonographic findings. Diagnoses: Laparoscopic surgical exploration revealed a hemorrhagic mass involving the right fallopian tube and the pelvic sidewall. Histopathological examination confirmed a diagnosis of primary tubal choriocarcinoma with pelvic peritoneal implantation. The patient was classified as International Federation of Gynecology and Obstetrics stage III. Interventions: Following diagnosis, the patient underwent multiple cycles of combination chemotherapy, specifically 5-fluorouracil + actinomycin D. Outcomes: Serial β-human chorionic gonadotropin monitoring demonstrated an excellent response to treatment, with normalization within 2 months. The patient remained in sustained remission throughout the follow-up period. Lessons: This case highlights the diagnostic challenge of differentiating gestational choriocarcinoma from ectopic pregnancy, especially in the context of primary tubal involvement, and underscores the critical role of histopathological examination in establishing a definitive diagnosis.