A rare case of simultaneous rectal and gastric carcinomas accompanied with inferior mesenteric arterioportal fistula: case report

BACKGROUND: Inferior mesenteric arterioportal fistula (APF) is rare as only 35 case reports in the literature. We herein presented a case of simultaneously double cancer in the rectum and stomach with inferior mesenteric APF, which is the first case report by searching using PubMed. Combination of interventional embolization and surgical operation seemed to be optimal treatment for avoiding postoperative complications and the curability. CASE PRESENTATION: A 66-year-old male with epigastric pain was admitted to a practitioner. He underwent a gastroscopy with biopsy, and cancer located in the lesser curvature of the gastric cardia was found. Enhanced CT did not reveal wall thickening of the stomach and distant metastases, but several swollen lymph nodes were observed in the right cardia. In the arterial phase, dilation of inferior mesenteric vein (IMV) and superior rectal artery (SRA) were noted, which raised suspicions of an arterioportal communication. Colonoscopy revealed a type 2 rectal tumor located 12 cm from the anal verge. The histological diagnosis of well-differentiated tubular adenocarcinoma was confirmed by biopsy. At a first step, we planned to perform a radiological embolization of inflow vessels to APFs except for SRA. Additionally, we determined the interval time of 1 month between the first low anterior rectal resection and the sequential gastrectomy for the purpose of decreasing portal pressure. The postoperative course was uneventful without hemorrhagic complications, and S-1 was taken internally 1 year as adjuvant chemotherapy for gastric cancer. The patient still lives without recurrence of this cancer with APF and portal vein thrombosis 2.5 years after the aforementioned surgeries. CONCLUSION: Inferior mesenteric APF and/or arteriovenous fistula (AVF) would be consisted of the several inflow arteries as superior rectal, internal iliac, and median sacral arteries, and outflow veins as inferior mesenteric, internal iliac, and median sacral veins. To determine the therapeutic strategy for left-sided colorectal cancers with abnormal vessel communications of the pelvis, it is significant to comprehend distribution and component vessels of APF and/or AVF.