Oral squamous papillomas: detection of HPV DNA by in situ hybridization

Oral squamous papillomas were segregated from other papillary lesions on the basis of histopathologic features. Twenty representative papillomas were evaluated for the presence of papillomavirus genus-specific antigen with the use of an immunoperoxidase technique. These same tumors were analyzed for human papillomavirus (HPV) types 2, 4, 6, and 11 with biotinylated full-length double-stranded DNA probes by in situ hybridization. Only one case exhibited papillomavirus antigen reactivity. Alternatively, seven of twenty cases (35%) yielded positive results for HPV 6 or 11 DNA; one papilloma exhibited a dual infection with both HPV 2 and 6 when assayed under conditions of high-stringency hybridization. It is concluded that some oral squamous papillomas harbor HPV genotypes akin to those encountered in genital tract condylomas. Viral DNA can be detected in the absence of capsid antigen immunoreactivity, thereby obviating the use of antigen detection assays for determining the presence or absence of virus.