Human papillomavirus (HPV) DNA in focal epithelial hyperplasia by in situ hybridization

Eighteen cases of focal epithelial hyperplasia (FEH) were investigated for the presence of human papillomavirus (HPV) group specific antigen by immunocytochemistry and HPV types 1, 6, 11, 13, 16, 18 and 32 by DNA in situ hybridization employing biotinylated probes. Seven (39%) specimens demonstrated the presence of HPV group specific antigen. Fifteen (83%) specimens were positive for HPV DNA: 9 (60%) showed HPV 32, of which 6 were on non-keratinized mucosa and 3 on border of keratinized and non-keratinized mucosa; 5 (33%) showed HPV 13, 4 lesions on keratinized mucosa and 1 on non-keratinized mucosa; 1 (7%) specimen on non-keratinized mucosa showed HPV-11 related. Two specimens on different sites from one patient showed the same HPV type and one patient had, in addition to FEH, a squamous papilloma also demonstrating the same HPV type. Results show a specific HPV distribution pattern in the epithelium indicating areas of high viral concentration adjacent to areas of low or no viral concentration. This study also indicates the possibility of tissue-site specificity or a latent infection and the possibility of a yet unidentified HPV type associated with FEH. It is suggested that future monitoring of patients be carried out with special reference to HPV type and anatomical distribution pattern for FEH lesions.