Rare case of colorectal polyposis

Authors of the case:

MD Consultant Pathologist Ugnius Mickys; Resident doctor Veslava Senina

Case report and histopathological evaluation

58 years old male was found traces of blood in stool during early diagnostic program for colorectal cancer. Colonoscopy revealed large number of eroded colorectal polyps. A biopsy was performed which revealed lesions composed of elongated, hyperplasic-appearing mucosal crypts with a mixed inflammatory infiltrate in the lamina propria. The surface of the lesion was ulcerated with a characteristic overlying “cap” composed of inflammatory exudate with granulation tissue, fibrin, mucus and leukocytes. Patient was treated with Sulfasalazine; H. Pylori eradication was also performed. Unfortunately, the patient's condition has deteriorated – he developed tenesmus and diarrhea with blood and mucus. Few colonoscopies were performed that showed disease progression – number of polyps increased significantly. Therefore a decision to perform a resection of an affected colonic segment was made. Gross inspection of resected specimen showed 20 cm of recto-sigmoid colon with multiple flat and slightly elevated flat polyps, with size variation from 0,8 cm to 5 cm. Microscopic examination revealed same lesions as diagnosed before.


CAP polyposis.


So called CAP polyposis is a rare condition that was first described in 1985, since then less than 100 cases have been reported in the literature. It is important to recognize this condition because of benign behavior of the lesion. The differential diagnosis of the lesion includes ulcerative colitis with inflammatory pseudopolyposis, tubulovillous adenoma, malignancy and infection. The etiology of the lesion still remains unknown, but few theories are considered. Probably one of the first theories is CAP polyposis association with bowel inflammatory response, treatment with anti-inflammatory drugs was primary commenced. The lesion may be associated with abnormal colonic motility due to straining during defecation and may be related to so called mucosal prolapsed syndrome. Another theory is association with infectious agents, although no pathogens were identified till date. Some authors noticed association with H. pylori infection, because after eradication of bacteria in stomach, remission of CAP polyps in colon was noted. No H. pylori bacteria were cultivated out of colon, though.  Gut dysbiosis-associated polyposis is also a matter of consideration. Some authors note disease regression after antibiotic administration, so microbiome–targeted therapy may be helpful in treatment of this lesion.


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