In situ DNA hybridization for cytomegalovirus in colonoscopic biopsies.

We reviewed colonoscopic biopsies of the lower gastrointestinal tract performed during a two-year period. Those representing neoplasia were excluded. Formalin-fixed paraffin-embedded biopsy specimens from 53 patients were studied by in situ DNA hybridization for cytomegalovirus (CMV) using commercially available biotinylated DNA probes detected by an avidin-biotin peroxidase technique. Nine of the patients were severely immunocompromised: four had acquired immunodeficiency syndrome, three had ulcerative colitis and were receiving high-dose steroid therapy, one was a bone marrow transplant recipient, and one had idiopathic pulmonary fibrosis and was receiving therapy with prednisone and cyclophosphamide. Four of these had evidence of CMV infection by routine histology and DNA hybridization. Three additional immunocompromised patients had evidence of CMV infection by DNA hybridization alone. Forty-four patients had inflammatory conditions or ulcerations of the lower gastrointestinal tract. Six of these had evidence of CMV by DNA hybridization alone. Histologically normal as well as enlarged and cytomegalic cells were probe positive, and the cells were sparse to numerous in number. They were found in the epithelium and/or lamina propria. This technique was demonstrated to be applicable to routinely processed colonic biopsy specimens.