Unusual gestational choriocarcinoma arising in an interstitial pregnancy

INTRODUCTION: Choriocarcinoma is a highly malignant trophoblastic neoplasm. Its association with ectopic pregnancy is very rare and usually with aggressive behavior. PRESENTATION OF CASE: We report a new case arising in an interstitial pregnancy occurring in a 46-year-old woman. The patient was admitted for severe pelvic pain and abundant metrorrhagia. One month ago, she had had a laparoscopic resection of an interstitial pregnancy subsequent to failure of chemotherapy by methotrexate. The raise of serum βhCG level and the hyperechoic intrauterine mass were in favor of gestational trophoblastic disease. Urgent laparotomy was performed for circulatory collapse. Hysterectomy was done. Histological examination revealed a choriocarcinoma. The patient underwent chemotherapy. Two years later, neither metastasis nor recurrence was detected. DISCUSSION: Clinical diagnosis of primary interstitial choriocarcinoma is difficult, since it is rare and manifesting by non-specific abnormal vaginal bleeding. Imaging findings are also not helpful in ectopic location. The frequency of metastasis is related to the delayed diagnosis. Serial measurement of βhCG level was the most useful marker of diagnosis and follow up. Histopathological examination remains the only tool of the precise diagnosis. Choriocarcinoma has a very good prognosis even in advanced stages, since it is very chemosensitive. CONCLUSION: The current trend of the treatment of ectopic pregnancy by conservative surgery requires adequate monitoring of βhCG and careful examination of pathologic specimens to avoid misdiagnosis of ectopic gestational trophoblastic disease.