Synchronous Colorectal Carcinoma: Case Report and Literature Review

Abstract

Synchronous colorectal carcinoma (sCRC) is defined as multiple malignant colorectal tumors that occur simultaneously or in a heterochronous manner. In comparison to patients with solitary colorectal carcinoma (CRC), the incidence of sCRC is rare. At present, the literature presenting case reports of patients with SC remains limited. Here, we present three cases of sCRC. The first patient was admitted because of a 5-month history of abdominal pain associated with difficult defecation. PET-CT and colonoscopy revealed a mass lesion of the splenic flexure of colon, and another mass in the sigmoid colon. Postoperative pathology confirmed that there are malignant characteristics in both lesions. The second patient suffered from with fatigue for more than two years. Abdominal contrast enhanced CT showed irregular thickening of the ascending colon wall, and colonoscopy revealed a tumor in the patient’s rectum and many polyps in the sigmoid colon. Postoperative pathology confirmed a moderately differentiated adenocarcinoma of the rectum and ascending colon. The third patient exhibited hematochezia for one year. Both rectal magnetic resonance imaging (MRI) and colonoscopy indicated the presence of two lesions in the rectum. Postoperative pathology confirmed two malignant tumors in the rectum. The literature review provided in this manuscript summarizes the available information on sCRC prevalence, clinical manifestation, diagnosis, pathology, treatment, and the molecular mechanism features of sCRC. At present, serrated adenoma, hyperplastic polyps, ulcerative colitis, and Crohn’s disease are considered to be closely related to sCRC. Microsatellite instability and gene mutation are two molecular mechanisms that give rise to sCRC.