ADENOVIRUS COLITIS IN HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION - AN UNDERDIAGNOSED ENTITY

Adenovirus infection of the gastrointestinal tract in human immunodefi ciency virus (HN)-infected patients is rarely reported, probably becau se of a lack of familiarity of most pathologists with diagnostic crite ria during routine light microscopy and possible misidentification as cytomegalovirus infection. We studied colonoscopic biopsy specimens fr om 135 HIV-infected patients with clinically suspected cytomegalovirus colitis during a 4.5-year period to morphologically identify the pres ence of adenovirus infection. Immunohistochemical staining for adenovi rus was performed for confirmation on all suspected cases. Adenovirus infected cells showed characteristic amphophilic or eosinophilic nucle ar inclusions, predominantly affecting the surface epithelium and char acteristically involving goblet cells. Sixteen cases showed morphologi c features of adenovirus infection, all confirmed by immunohistochemis try. Twelve cases also showed cytomegalovirus infection, whereas 4 sho wed adenovirus alone. In 10 cases, adenovirus colitis was not recogniz ed during initial routine histopathologic diagnostic evaluation. Adeno virus inclusions also were discovered in the stomach, the duodenum, an d the liver in single cases. Conclusions are as follows: (1) Adenoviru s colitis has been underdiagnosed at our institution and, we suspect, in general. (2) The morphologic features and nuclear inclusions of ade novirus colitis are characteristic and can be identified reliably by r outine light microscopy. (3) Adenovirus infection also may be diagnose d morphologically in extracolonic sites, such as the stomach, the smal l intestine, and the liver. (4) Coinfection of adenovirus with cytomeg alovirus and other agents is seen frequently, but, less frequently, ad enovirus may be identified as a sole pathogen.