Human papillomavirus. Frequency and distribution in plantar and common warts

Fifty-nine (24 plantar, 35 common) warts surgically excised from 44 patients (15 female, 29 male), 18 to 32 years old, were examined by electron microscopy (EM) for papillomavirus particles and by fluorescent antibody (FA) and peroxidase-antiperoxidase (PAP) tests for human papillomavirus type 1 (HPV-1)-specific antigens and papillomavirus genus-specific (common) antigens. Fifty per cent of plantar warts and 52 per cent of common warts were positive for HPV by EM. When examined by FA and PAP for genus-specific antigens, 58 per cent of plantar warts and 68 per cent of common warts were positive. Fifty per cent of plantar warts and 11 per cent of common warts were caused by HPV-1 as determined by reactivity with HPV-1 type-specific antiserum. All warts positive by EM were positive by FA and PAP. Sampling error accounted for warts positive by FA and PAP but not by EM. Forty-two per cent of plantar warts and 31 per cent of common warts were negative by both EM and FA and PAP. The warts caused by HPV-1 contained more virus and were more clinically aggressive than warts caused by other HPV. This study shows that the results obtained by the PAP technique using papillomavirus genus- and type-specific antisera on formalin-fixed, paraffin-embedded tissue available to the diagnostic pathologist are concordant with the results obtained by methodology usually available only to the experimental pathologist.