29 November 2007 – Case of the Week #102


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We thank Dr. Michael W. Robles, Ameripath North Texas (USA) for contributing this case.  To contribute a Case of the Week, please email info@PathologyOutlines.com with the clinical history, your diagnosis and microscopic images in JPG, GIF or TIFF format (send as attachments, we will shrink if necessary).  Please include any other images (gross, immunostains, etc.) that may be helpful or interesting.  We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US dollars) for your time after we send out the case.  Please only send cases with a definitive diagnosis, and preferably cases that are out of the ordinary.


Case of the Week #102


Clinical History


A 28 year old man had a history of ulcerative colitis with severe dysplasia.  At surveillance endoscopy, the gastroenterologist saw continuous ulcerative colitis in the rectum, sigmoid and descending colon.  Multiple colonic biopsies were obtained.


Micro images:  image #1#2#3#4 


What is your diagnosis?




























Cap polyposis, negative for ulcerative colitis or dysplasia




Cap polyposis was first described in 1985 (Br J Surg 1985; 72 (Suppl) S133).  It is rare and characterized by multiple, distinctive inflammatory rectosigmoid polyps (gross image).  Its etiology is unknown, although it may be associated with mucosal prolapse (Gut 1993;34:562).  It often presents with mucoid or bloody diarrhea and hypoproteinemia.  Colonoscopy shows multiple sessile rectosigmoid polyps with adherent white flecks, with normal intervening mucosa (Endoscopy 2001;33:262).


Microscopically, cap polyposis has inflamed mucosa with tortuous, elongated crypts, attenuated towards the mucosal surface, with a granulation tissue ”cap” on the mucosal surface   The differential diagnosis includes other polyposis syndromes, such as amebic colitis, antibiotic associated colitis or inflammatory bowel disease. 


Treatment has traditionally been polypectomy or partial colectomy (Dis Colon Rectum 2004;47:1208).  However, recent case reports have demonstrated dramatic results from medical treatment in patients with H. pylori gastritis (Helicobacter 2004;9:651) and by using infliximab, an antibody to tumor necrosis alpha (Gastroenterology 2004;126:1868).




Nat Pernick, M.D., President
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