Collagenous colitis: jejunal and colorectal pathology

Area of Science:

• Gastroenterology
• Immunology
• Pathology

Background:

• Collagenous colitis is an inflammatory bowel disease characterized by a thickened subepithelial collagen layer.
• The association between collagenous colitis, coeliac disease, and lymphocytic colitis requires further investigation.
• Understanding the immune cell infiltrate in collagenous colitis is crucial for diagnosis and management.

Purpose of the Study:

• To investigate the association between collagenous colitis and coeliac disease or lymphocytic colitis.
• To characterize the lymphocyte subsets and macrophages in collagenous colitis.
• To determine the colorectal distribution of collagenous colitis and the diagnostic sufficiency of sigmoidoscopic biopsy specimens.

Main Methods:

• Retrospective analysis of clinical data and colorectal biopsy specimens from 38 collagenous colitis patients.
• Review of small bowel biopsy specimens from 10 patients.
• Immunostaining of mucosal lymphoid infiltrate using relevant antibodies on formalin-fixed and fresh biopsy specimens.

Main Results:

• Four out of 10 patients with collagenous colitis had coeliac disease, significantly higher than the general prevalence.
• Collagenous colitis did not respond to gluten withdrawal.
• Increased intraepithelial lymphocytes in collagenous colitis were predominantly CD8 positive cells.
• The disease distribution was independent of anatomical site, with >90% diagnostic yield from sigmoid colon or rectal biopsies.

Conclusions:

• A high incidence of coeliac disease necessitates jejunal biopsy in collagenous colitis patients, especially if symptoms persist.
• A minority of patients presented with a mixed pattern of lymphocytic and collagenous colitis.
• Intraepithelial lymphocytes in collagenous colitis are CD8 positive.
• Rectal or sigmoid colon biopsies are diagnostic for collagenous colitis in over 90% of cases.