Endoscopic features of rectal mucosal prolapse syndrome (RMPS): differentiation with malignant rectal tumor

Abstract

Background: Rectal mucosal prolapse syndrome (RMPS) usually manifests as rectal bleeding, and tenesmus. Endoscopically it could be easily misdiagnosed with malignant rectal tumor (MRT). This study aims to investigate factors to distinguish RMPS and MRT, and explore endoscopic features of RMPS. Methods: Patients endoscopically diagnosed as rectal lesions, mass, or tumors, were retrospectively collected. Clinical information, endoscopic images, histologic reports were reviewed. Patients endoscopically and histologically diagnosed as RMPS were included for phenotype classification. Results: 826 patients were enrolled, among them 755 (91.4%), 22 (2.7%), 10 (1.2%) and 39 (4.7%) were respectively diagnosed with MRT, RMPS, endometriosis, and neuroendocrine tumor. Compared with MRT, patients with RMPS were significantly younger (33.5 vs. 62, P< 0.001), and lesions were significantly smaller (2cm vs. 3cm, P=0.007). Moreover, clinical course of patients with RMPS would be significantly longer than those with MRT (12 months vs. 3 months, P<0.001). Morphologically, we classified lesions of RMPS into five phenotypes, that is, lesions with circumferential stenosis (19.4%), protrusions (41.7%), both ulcers and protrusions (11.1%), ulcers (11.1%), flat manifestations (16.7%). Protruding lesions were more frequently observed in females (P=0.039), while ulcerative lesions were found involving a smaller proportion of the rectal circumference (P=0.028). Lesions with only ulcers were found with a shorter distance compared with those with only protrusions (5cm vs. 10cm, P=0.034). Conclusions: Age, clinical course, and size of the lesion, could be applied to distinguish MRT and RMPS. Five phenotypes are introduced and features of ulcers/protrusions are further explored.