Gestational Choriocarcinoma Arising from an Ectopic Pregnancy: A Rare and Aggressive Malignancy Presenting with Pulmonary Metastasis

Background: Gestational choriocarcinoma (GC) is a rare, aggressive form of gestational trophoblastic neoplasia (GTN), typically linked to molar pregnancies but occasionally following term pregnancies, miscarriages, or ectopic gestations. Ectopic pregnancies occur in 1.3–2% of pregnancies, but GC from ectopic implantation is extremely rare, with an incidence of approximately 1 in 1,000,000 pregnancies. Early recognition is crucial due to its high metastatic potential and excellent response to chemotherapy. Case Presentation: A 37-year-old multiparous woman presented three months post-laparotomy for an ectopic pregnancy with hemoptysis, vaginal bleeding, and severe anemia. Imaging showed "cannonball" pulmonary metastases, and β-hCG levels exceeded 100,000 IU/L. Retrospective histopathology from the prior surgery confirmed choriocarcinoma at the ectopic implantation site near the uterine fundus. Staged as FIGO IIIB:1 with a WHO risk score of 8, she began treatment with methotrexate and folinic acid, with plans to escalate to multi-agent EMA-CO chemotherapy. Discussion: Diagnosing GC in extra-uterine sites is challenging due to its rarity and nonspecific symptoms, often mistaken for common gynecological issues like ovarian cysts or routine ectopic pregnancies. Retrospective pathology was key in this case. GC’s vascular and invasive nature leads to frequent metastases, particularly to the lungs, brain, liver, and vagina. Despite its aggression, timely chemotherapy yields an 85% remission rate in high-risk cases. Serum β-hCG is critical for diagnosis and long-term monitoring. Conclusion: Routine histopathological examination of ectopic pregnancy specimens and vigilant β-hCG follow-up are essential to detect rare, curable malignancies like GC. Early diagnosis and staging are vital for effective therapy and improved outcomes, especially in resource-limited settings.