Inflammatory Cloacogenic Polyp: A Distinctive Cause of Hematochezia

Abstract

Inflammatory cloacogenic polyp (ICP) is a special type of benign polypoid growth arising from the transitional zone of the anorectal junction. This lesion was first described by Lobert and Appleman in 1981 and It is believed to result from a mucosal prolapse that produces repetitive local trauma and ischemic injury leading to chronic inflammation. Typically, it presents with rectal bleeding, tenesmus and altered bowel habits resembling anorectal neoplasia clinically and macroscopically. We describe a rare case of hematochezia caused by an ICP that was ovelooked on direct vision colonoscopic exam until a retroflexion was done. 43 year old man presents with intermittent rectal bleeding and tenesmus of one year duration. Blood was mixed with stools and symptoms worsened over the last 6 months. Review of system was significant for chronic constipation but he denied weight loss, melena, abdominal pain, fever or upper gastrointestinal symptoms. Previously healthy, he denied taking any medications, drinking alcohol, smoking cigarettes or any family history of colon cancer. Vital signs were normal. Blood count and chemistry profile were unremarkable, namely no anemia. Colonoscopy was performed to show unremarkable colon on direct vision till cecum, however upon retroflexion in the rectum a frond like, semi-pedunculated polypoid lesion was noted at the anorectal junction. The lesion was then examined carefully in direct vision: it measured 15 mm and appeared inflammatory with areas of superficial ulcerations (Fig 1). Complete resection of the polyp was performed by a snare cautery. Histopathology disclosed prolapsed colonic mucosa with disrupted muscularis mucosa, fibromuscular and epithelial hyperplasia, dense inflammatory infiltrate within the lamina propria consistent with inflammatory cloacogenic polyp, no dysplasia (Fig 2&3). Patient's rectal bleeding resolved thereafter. Inflammatory cloacogenic polyps are rare and unique inflammatory anorectal lesions with an estimated annual incidence of 1/100.000. ICPs constitute a diagnostic challenge due to their clinical and macroscopic similarities to adenomas and anorectal neoplasms. These lesions occur around the transitional zone in the lower anorectum and hence they may be overlooked at colonoscopy, as in our case, unless an endoscopic retroflexion maneuver is performed. Endoscopists should be familiar with this entity, which should be considered in the differential diagnosis of anorectal polypoid lesions.Figure: (A) Colonoscopy image of the lesion upon retroflexion (B) Direct vision colonoscopy image showing areas of inflammation and superficial ulceration.Figure: Histopathology (H$E stain) disclosing active chronic inflammation with a prominent underlying reactive lymphoid follicle (Arrow).Figure: Microscopic examination showing a disrupted muscularis mucosa, fibromuscular and epithelial hyperplasia, with dense inflammatory infiltrate within the lamina propria consistent with inflammatory cloacogenic polyp.