Collagenous colitis.

Collagenous colitis is characterized clinically by chronic watery diarrhea and pathologically by colonic mucosal subepithelial collagen deposition. We report a 72-year-old woman who had collagenous colitis associated with chronic watery diarrhea. She received a non-steroidal anti-inflammatory agent (sulindac) because of rheumatoid arthritis. Histological examination of biopsy showed a thick subepithelial collagen layer with lymphocytes, plasma cells, and infiltration of a few eosinocytes in the lamina propria. These findings led to the diagnosis of collagenous colitis. After treatment with salazosulfapyridine, her bowel movement became normalized and mucosal subepithelial collagen deposition disappeared.