This study reports the histological features helpful in diagnosing microscopic colitis. Rectal biopsy specimens from 14 patients with microscopic colitis, 14 with active ulcerative colitis and 14 without colonic inflammation were pooled and then assessed by three observers according to a predetermined protocol. Inter-observer agreement was good except for Paneth cell metaplasia and endocrine cell metaplasia. Compared with healthy tissue, microscopic colitis showed a significant (p less than 0...