DIAGNOSTIC DIFFICULTY ARISING FROM RECTAL RECOVERY IN ULCERATIVE-COLITIS

Aims-To ascertain whether the dogma that a normal rectal biopsy preclu des a diagnosis of ulcerative colitis is correct. Methods-Rectal biops y specimens from a prospective group of 24 asymptomatic patients, with an established diagnosis of ulcerative colitis, were examined in a bl inded study alongside 10 normal rectal biopsy specimens from an age an d sex matched patient cohort without ulcerative colitis. Each biopsy s pecimen was assessed by three pathologists and ascribed to one of four categories: normal; borderline abnormality (one or more minor non-spe cific abnormalities which, when combined, did not fulfil the minimal a cceptable criteria for a diagnosis of ulcerative colitis); minimal fea tures of chronic ulcerative colitis; and unequivocal ulcerative coliti s. Results-Two patients with ulcerative colitis had normal biopsy spec imens; nine specimens were categorised as borderline abnormality, one as showing the minimal changes of chronic ulcerative colitis, and 12 a s having the typical changes of chronic ulcerative colitis. Thus, 11 ( 46%) of the 24 patients had a rectal biopsy specimen that was devoid o f the acceptable attributes on which a diagnosis is established, despi te a confident previous diagnosis. Ten of these 11 cases had disease l imited to the rectum. Review of all previous histological biopsy speci mens (n = 164) and clinical data, including drug treatment, failed to identify any attributes that might be prognostic markers for future re ctal mucosal healing. Conclusions-A normal rectal biopsy specimen, tho ugh uncommon, may occur in longstanding colitis. Moreover, in 46% of t hese asymptomatic but established cases the degree of healing may prec lude a diagnosis of ulcerative colitis without comprehensive clinical and radiological details. Pathologists need to be aware of this minima l end of the spectrum of disease.