To determine the utility of immunohistochemistry (IHC) for the diagnosis of viral infections in surgical pathology specimens lacking characteristic viral cytopathic effects.
Five years of cases at an academic medical center were reviewed for the use of IHC to detect cytomegalovirus (CMV), herpes simplex virus 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), adenovirus, or polyomavirus (ie, BK or JC).
In total, 1,636 viral IHC stains were ordered on 1,099 specimens from 957 cases. Altogether, 134 (8.2%) stains were positive, including 59 (7.9%) of 749 for CMV, 34 (8.9%) of 384 for HSV-1 and HSV-2, 16 (11.5%) of 139 for VZV, three (1.4%) of 210 for adenovirus, and 22 (14.3%) of 154 for polyomavirus. In 101 (75.4%) of 134 cases, viral cytopathic effect (VCPE) was readily identifiable on H&E slides. No significant changes in clinical care occurred in any of the cases without definitive VCPE that had positive staining cells on IHC.
These findings suggest that IHC for viral infections without a high degree of clinical or histologic suspicion is unnecessary in most cases.