Complications of collagenous colitis

Figure 1 Gross macroscopic appearance of colonic mucosa in collagenous colitis. During colonoscopy, the mucosa may appear virtually normal with minimal alteration in the clarity of the vascular pattern. Diagnosis depends on microscopic evaluation of a colonic biopsy, not the macroscopic appearance of the colonic mucosa.

Figure 2 Lower and higher power photomicrographs of the colonic mucosa in collagenous colitis. A mucosal inflammatory process is present with well preserved crypt architecture. Note the subepithelial mucosal band of collagen material.