P2006 - Rapid Weight Loss: A Case of Severe Cap Polyposis Syndrome

Cap polyposis syndrome (CPS) is a rare, benign condition with a hallmark appearance characterized by inflammatory colonic polyps covered by a white exudate or “cap,” from which the condition derives its name. We present a case of CPS in a 65-year-old healthy female presenting with two-year history of bloody, mucoid diarrhea and rectal spasms. This case highlights the debilitating impact of CPS with a high polyp burden on an individual's well-being, despite its benign nature. Consequently, a surgical approach was necessary to alleviate her symptoms.

A 65-year-old female presents to our GI clinic with concerns of pelvic pain triggered by bowel movements, bloody, mucoid diarrhea, and 35-pounds weight loss over two years. Physical exam with mild generalized abdominal tenderness. Labs revealed mild hypoalbuminemia with normal inflammatory markers and stool studies. MR defecography and anorectal manometry revealed rectal dyssynergia. She underwent multiple colonoscopies revealing many polyps ranging in size from 0.5 to 2 cm. They exhibited an exudative surface and spanned a few cm proximal to the anal canal to 20 cm into the colon. Four polyps were removed with pathological analysis revealing inflammatory type polyps with one showing low-grade dysplasia. Due to the increase in polyp burden and persistent symptoms, she underwent laparoscopic low anterior resection with colorectal anastomosis and diverting loop ileostomy, resulting in significant relief. Colonoscopy six months later revealed diversion colitis and mild erosions throughout the colon. The descending colon demonstrated mucosal erythema, friability with many superficial ulcerations, and one tubular adenomatous polyp. Pathology results of the left colon revealed colitis with crypt architect distortion, superficial erosions, and inflamed granulation tissue concerning for ischemia – a proposed mechanism of CPS pathogenesis.

CPS is a rare and benign condition. Patients commonly present with bloody, mucoid diarrhea, abdominal pain, and weight loss. It should be suspected in patients with erythematous colonic polyps with an adherent mucoid cap and is established by biopsy with findings of hyperplastic appearing glands with mixed inflammatory infiltrate and fibromuscular obliteration within the lamina propria. Given its similar presentation, CPS can often be misdiagnosed as IBD. Therefore, it is crucial to familiarize ourselves with this benign condition and adjust our management strategies accordingly.