Collagenous colitis and lymphocytic colitis

The most recently recognized and least understood forms of inflammatory bow el disease are two types of idiopathic microscopic colitis-collagenous coli tis and lymphocytic colitis. These disorders share many clinical and histol ogic features, but they have a few notable differences. Whether these are t wo distinct entities or different presentations of the same disease remains controversial. Bismuth subsalicylate is effective in some patients and tre atment is symptomatic and empirical in others. Unlike ulcerative colitis an d Crohn's disease, these forms of inflammatory bowel disease rarely require surgery. Ileostomy with or without colectomy is curative for the rare pati ent with severe symptoms that are refractory to medical measures. Collageno us and lymphocytic colitis are not associated with an increased risk of mal ignancy.