A Case of Choriocarcinoma Undergoing Laparoscopic Surgery Due to Suspected Peritoneal Pregnancy.

Extrauterine choriocarcinoma is uncommon and may be mistaken for a ruptured ectopic pregnancy. Rapid diagnosis is essential, as massive intraperitoneal bleeding can be fatal. Once histologically diagnosed, choriocarcinoma is highly chemosensitive. This case describes a 38-year-old woman who presented with sudden lower abdominal pain. Six weeks after her last menstrual period, serum human chorionic gonadotropin (hCG) was 28,834 mIU/mL. No intra-uterine gestational sac was found, and intraperitoneal bleeding was observed, suggesting an ectopic pregnancy. An emergency laparoscopic surgery revealed a blood clot and active bleeding on the peritoneal surface near the ileocecal region, which was resected. Histology revealed sheets of syncytiotrophoblasts and intermediate trophoblast cells without villi, and immunohistochemistry was diffusely positive for Ki-67 and hCG, confirming primary peritoneal choriocarcinoma. Staging imaging revealed no other lesions. The patient received four cycles of MEA chemotherapy (methotrexate, etoposide, actinomycin D) at three-week intervals, resulting in sustained hCG normalization and no evidence of recurrence at follow-up. Primary peritoneal choriocarcinoma should be considered in the differential diagnosis of intraperitoneal bleeding during early pregnancy. Even when ectopic pregnancy is suspected, the excised tissue must be submitted for histopathological examination so that chemotherapy can be initiated promptly in case of choriocarcinoma.