An analysis of the reliability of detection and diagnostic value of various pathological features in Crohn's disease and ulcerative colitis.

Two pathologists have independently applied 95 separate pathological criteria to 50 cases of inflammatory large bowel disease firmly diagnosed clinically as 25 cases of Crohn's disease and 25 cases of ulcerative colitis. The observer agreement in the recording of each feature has been calculated and correlations have been made between the pathological features and the final agreed diagnosis in order to obtain an estimate of the value of each feature in differential diagnosis. The features which have been found to be most accurately observed and useful in the diagnosis of Crohn's disease include confluent linear ulcers, deep fissures, an aggregated inflammatory pattern, and sarcoid-like granulomata. The features which have been shown to be most accurate and valuable in the diagnosis of ulcerative colitis include a ;healed granular' mucosa, a continuous inflammatory pattern, an irregular gland pattern, and the absence of fissures. The authors consider that the use of such accurate and valuable pathological criteria in the examination of inflammatory bowel disease would facilitate retrospective correlation with the clinical findings and help to clarify those intermediate cases which are at present a source of diagnostic difficulty.