Introduction:
Primary rectal choriocarcinoma is an extremely rare malignancy. The association of these neoplasms in patients with inflammatory bowel disease (IBD) has not been reported.
Presentation of case:
A 34-year-old female with history of Ulcerative Colitis (UC) gave birth to a male fetus. She had postpartum bleeding and high level of beta-human chorionic gonadotropin (βhCG) was detected. Although initial investigations failed to confirm molar pregnancy, abnormal uterine bleeding and high βhCG level necessitate chemotherapy administration. She did not respond to chemotherapy sessions accordingly. Meanwhile, the patient experienced rectorrhagia and colonoscopy revealed a firm submucosal polypoid lesion 8-10 cm from the anal verge. The multidisciplinary team candidate the patient for total proctocolectomy and ileal pouch anal anastomosis. Although postoperative course was uneventful and βhCG level dropped but it showed a rising pattern in follow ups. Chemotherapy was planned but there was not suitable response. Unfortunately, the patient passed away 20 months after the initial diagnosis.
Discussion:
Pathology report indicated the coexistence of moderately differentiated tubular adenocarcinoma and choriocarcinoma. We assume previous history of UC might have put her at higher susceptibility to develop carcinoma and this poorly differentiated carcinoma has led to choriocarcinoma. Considering the fact that in most cases of colorectal choriocarcinoma, choriocarcinomatous differentiation was found alongside colonic adenocarcinoma made dedifferentiation theory to be the most acceptable explanation.
Conclusion:
The adenocarcinoma of the colon and rectum in the setting of IBD may become so dedifferentiated that gain some characteristics of germ cell tumors.