Cytological recognition of herpes simplex virus infection in bronchoscopic samples from the respiratory tract

Cytological features suggesting herpes simplex virus (HSV) infection in samples obtained at bronchoscopy have been described only very rarely in routinely processed samples. We report four cases where evidence of HSV infection was identified morphologically in samples processed using thin-layer techniques, with polymerase chain reaction confirmation of the presence of virus in three cases. We suggest that the increased morphological clarity provided by this technique for processing these cytology samples may result in the morphological features of viral infection being seen more frequently. Pathologists reporting such samples need to be aware of this possibility in order to avoid potential misinterpretations. In addition, however, respiratory and intensive care physicians unused to receiving cytology reports indicating 'HSV infection' need to be aware that the significance is uncertain and in most cases it is likely to indicate the reactivation of a latent infection.