Primary colon adenocarcinoma with choriocarcinoma differentiation: a case report and review of the literature

BACKGROUND: Choriocarcinoma is an aggressive malignancy of trophoblastic tissue, typically of gestational etiology. Sporadic, nongestational cases are rarely found outside of the gonads. There are only 31 cases of primary choriocarcinoma of the colon reported in the literature. As a consequence of their rarity and aggressive nature, timely diagnosis and effective treatment have proved challenging, and prognosis is very poor. For that reason, we present a rare case with prolonged survival in the youngest reported patient . CASE PRESENTATION: A 26-year-old Caucasian woman presented with abdominal cramping and rectal and vaginal bleeding. Elevated serum human chorionic gonadotropin and an 8-cm right-sided mass seen on ultrasound suggested ectopic pregnancy. The patient was treated with methotrexate; however, her symptoms persisted, and her human chorionic gonadotropin levels continued to rise. Further workup showed a large mass of the sigmoid colon with multiple hepatic lesions suggestive of metastases. Preliminary pathology showed adenocarcinoma. Despite surgical resection and initiation of FOLFOX chemotherapy (folinic acid, fluorouracil, oxaliplatin), the patient had significant clinical deterioration, and her human chorionic gonadotropin increased exponentially. Further pathological review showed two distinct phenotypes: adenocarcinoma merging with choriocarcinoma. The result of evaluation of the metastatic lesions was also positive for choriocarcinoma. Treatment was promptly changed to a choriocarcinoma-targeting chemotherapy regimen of EMA/CO (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine), resulting in rapid and dramatic response. The patient had mild progression after 1 year and was switched back to FOLFOX with bevacizumab. After five cycles, scans showed further progression, and the patient was started on third-line therapy with FOLFIRI (folinic acid, fluorouracil, irinotecan) and bevacizumab. Eighteen months after her diagnosis, the patient was alive and maintaining an overall response. CONCLUSIONS: Our patient achieved a marked response and prolonged survival. Although a comprehensive review of the literature showed that survival with these tumors has improved over the past 10 years, prognosis remains poor. Currently, there is no established algorithm for the management of these rare tumors, but both the literature and our patient’s case indicate that a choriocarcinoma-targeted regimen is critical for survival. Further evaluation of these rare tumors is warranted in order to identify pathological patterns that may help in the diagnosis, management, and survival of these malignancies.