LYMPHOCYTIC COLITIS - A DEFINABLE CLINICAL AND HISTOLOGICAL DIAGNOSIS

We reviewed colorectal biopsies and clinical records from 36 patients with chronic watery diarrhea who had been diagnosed as having microsco pic colitis and compared their histologic features with the more detai led and precise criteria for lymphocytic colitis. Published pathologic criteria for lymphocytic colitis were applied to the biopsies and com pared. Focal or diffuse nature of the lymphoid infiltrate were noted s eparately. The focal lymphoid infiltrate was related to lymphoid aggre gates in the lamina propria of the mucosa. Eighteen cases had focal ly mphoid cell infiltration, and 16 of them had associated diverticula, p olyps, or both. Eighteen cases had diffuse lymphoid cell infiltration, and six of them had diverticula or polyps. Results indicate that foca l cellular infiltration strongly predicts associated diverticula or po lyps. The group with no diverticula or polyps most closely conformed t o histologic criteria for lymphocytic colitis (Kruskal-Wallis P < 0.02 ). We conclude that lymphocytic colitis comprises a well-defined group of cases within the large and less-defined group of microscopic colit is.