Colonic histopathology in untreated celiac sprue or refractory sprue: Is it lymphocytic colitis or colonic lymphocytosis?

Colonic histopathology in some patients with untreated celiac sprue and ref ractory sprue has been said to be indistinguishable from lymphocytic coliti s, but there have been no objective comparisons on which this is based. The purpose of this study was to determine the prevalence and to characterize the nature of colonic histopathology at the time of diagnosis in patients w ith celiac or refractory sprue. Colonoscopic biopsy specimens obtained at t he time of diagnosis from 16 patients with celiac sprue, six patients with refractory sprue, nine patients with lymphocytic colitis, and five normal c ontrols were analyzed blindly by histological and morphometric methods, qua ntitating the number and specific subtypes of inflammatory cells within the lamina propria and epithelium. Immunoperoxidase staining of intraepithelia l lymphocytes with a monoclonal antibody to CD8 also was performed. Three o f 16 patients with untreated celiac sprue (19%) were thought to have coloni c histological abnormalities, which by morphometry consisted of slightly in creased numbers of lymphocytes in the surface epithelium and lamina propria , many of which were CD8-positive. These abnormalities were distinguishable from lymphocytic colitis by the lack of increased overall lamina propria c ellularity and surface epithelial abnormalities, and by fewer intraepitheli al lymphocytes. In refractory sprue, colonic histological abnormalities wer e more frequent than in celiac sprue, occurring in four of six patients (67 %), more pronounced, and identical to those in the lymphocytic colitis synd rome. However, colonic intraepithelial lymphocytes in lymphocytic colitis w ere mostly CD8-positive, whereas those in the colitis of refractory sprue r arely were. Mild colonic lymphocytosis in patients with untreated celiac sp rue should be distinguished from lymphocytic colitis: by the lack of surfac e epithelial abnormalities, the lack of increased cellularity of the lamina propria, and the lack of ongoing watery diarrhea after treatment with a gl uten-free diet. In contrast, colonic histopathology in refractory sprue is indistinguishable from lymphocytic colitis, although immunohistochemical di fferences do exist. HUM PATHOL 29:1433-1440. Copyright (C) 1998 by W.B. Sau nders Company.