A 26-year-old woman diagnosed at 18 years of age with ulcerative colitis without requiring treatment. In October 2002 she presented new episodes of diarrhoea of 3-4 stools/day with red blood. Anamnesis by apparatus with no notable alterations. Rectal examination revealed an excrescent lesion 3-5 cm from the anal margin. HIV, lues, Epstein-Barr virus and cytomegalovirus serology were negative. Several colonoscopies were performed which revealed a rectal formation 2-3 cm from the anus with an ulcerated surface (anatomopathological report of an ulcerated lesion with signs of dysplasia in the epithelium covered by fibrinous-leukocytic material, inconclusive) and treatment was therefore instituted with dietary hygiene measures, corticosteroid enemas and even 5-ASA suppositories. A new colonoscopy revealed a mixed hyperplastic polyp-tubular adenoma of the rectum and the patient was referred for surgery, which was carried out in January 2004 with transanal resection of the lesion and the anatomopathological report of chronic non-specific inflammation.
After re-analysing the patient's history, given the discordance between the clinical and histological features of the lesion and its evolution over time, it was decided to review all the biopsy specimens by the same anatomopathologist, who found no evidence of villous adenoma or inflammatory bowel disease in any of the samples, and together with him, a diagnosis of "cap polyposis" was made.