CCP is a rare benign medical condition and its exact etiology is still unknown. It may occur at either mucosa or occasionally submucosa containing mucous cysts focally or diffusely[1].CCP can be divided into diffuse, segmental and localized[2]. The diffuse CCP often locates in the whole colorectal, segmental CCP states single or several segments of colorectal and localized CCP occurs in the rectum distant from anal verge 5-12cm[2]. In this case, the lesions located at ascending colon, hepatic flexure of the colon and transverse colon, which should be classified as segmental type.
The CCP patients may present with abdominal pain, hematochezia, change in bowel habits, diarrhea, mucous fluid and tenesmus[3]. The clinical symptoms could be atypical and even asymptomatic. What’s more, CCP was associated with several diseases, such as UC, IBD, radioactive enteritis, infectious colitis, colorectal ploypoid, and even colonic adenocarcinoma or GIST[4, 5]. The etiology of CCP is still unknown and may be related to congenital, inflammatory reaction or trauma[6, 7]. The isolated colonic ulcer in colonoscopy may be presented as polypoid mass slightly protruding from the enteric cavity, which is similar to intestinal cancer but rarely induces obstruction[1]. Mucous adenocarcinoma and mucous cyst can be distinguished by pathological examination. In this case, pathological features are cystic dilatation of ectopic glands and mucin pool in submucosa, which makes mucosa present as a polypoid which irruptive into antrum. In addition, enlarged glands or mucus are often surrounded by chronic inflammatory reactions or fibrosis hyperplasia[8].
Most CCP patients may be misdiagnosed due to its complexity, and can be recognized after long-term medical treatment or surgical resection, especially in the elder or patients with relevant family history. In this case, the process of diagnosis and treatment was complicated. There was no ulceration but only polyp lesion which protruded into antrum in the colonoscopy. The diagnosis was uncertain until biopsy. To a large extent, it relied on the fact that lesions were significantly shrink when reexamined. Notably, in this case, the etiology, treatment and recurrence are still not clear. It may work via following ways: Firstly, self-healing. Secondly, use of antibiotics. Thirdly, the remaining lesions were atrophied after a single resection. The hypothesis may improve the diagnosis of colon lesions. The mode of multi-disciplinary team also plays an important role for the diagnosis and treatment. It is effective to integrate the advantages of various disciplines.
In summary, the endoscopic and clinical features of CCP and GIST are presented. This case is an important reference for primary physician and pathologist to make correct diagnosis through initial endoscopic and pathological examination.