Collagenous Colitis : Differential Diagnosis

Comments:
The differential diagnosis of collagenous colitis includes: lymphocytic colitis (increased intraepithelial lymphocytes; absence of thickened subepithelial collagen); chronic inflammatory bowel disease (crypt distortion, inflammation and fibrosis in deeper layers of lamina propria and submucosa); solitary rectal ulcer/mucosal prolapse (crypt distortion, muscular proliferation, fibrosis in deeper layers of lamina propria); ischemic colitis (fibrosis and hyalinization of lamina propria, but without intraepithelial lymphocytes and plasma cells in lamina propria); and radiation colitis (hyalinization of lamina propria, telangiectatic blood vessels, atypia of endothelial cells and fibroblasts).

This image shows typical histologic features of collagenous colitis: thickened subepithelial collagen layer which appears as a hypocellular pink band under surface epithelium, increased lymphocytes and plasma cells in the lamina propria, and an intact crypt architecture. Image credit: Copyright ©2010 Michael Bonert, MD - Own work, CC BY-SA 3.0