Human papillomavirus infection and filaggrin expression in paraffin-embedded biopsy specimens of extragenital Bowen's disease and genital bowenoid papulosis.

Cutaneous Bowen's disease (BD) and genital bowenoid papulosis (BP) are considered as precancerous or cancerous lesions that are sometimes infected with human papillomavirus (HPV). We studied retrospectively paraffin-embedded sections of 11 samples of cutaneous BD and 6 samples of genital BP from the general population for HPV infection and filaggrin expression. Using in situ hybridization with biotinylated probes of HPV types 1, 2, 5, 6, 11, 16, and 18, under stringent and/or non-stringent conditions and a streptavidin-alkaline-phosphatase complex for hybrid detection, HPV DNA was detected in 6/17 cases (5 BD and 1 BP). Positive nuclei were located in intermediate or upper epithelial cell layers. HPV 16 was found in 2 cases of BD but associated either with HPV 2 or 18. Three additional lesions reacted only under non-stringent conditions; HPV could not be typed with the probes used. The positive case of BP reacted with the four probe types 1, 2, 16, 18 and was negative with HPV 6 or 11. Viral antigen was not detected by indirect immunofluorescence with a rabbit antiserum directed to group-specific viral capsid antigen. Differentiation disorders were observed in the intermediate and upper cell layers of these specimens, as shown by a reduced expression of filaggrin/profilaggrin, a marker of terminal differentiation, in extragenital BD (7/11 cases), and an increased expression in genital BP (4/5 cases) although viral DNA was not always detectable. This study shows that in situ hybridization is a valuable technique for HPV DNA detection and its typing in BD and BP lesions on deparaffinized sections. The positive nuclei were located in the cell layers that exhibited abnormal expression of differentiation. There is no relation between the HPV infecting type and the filaggrin expression.