Demonstration of multiple HPV types in laryngeal premalignant lesions using polymerase chain reaction and immunohistochemistry

Recent evidence has shown that human papillomavirus (HPV) is involved in bo th the development of carcinoma and in premalignant mucosal lesions of the oral cavity. This study examined the relationship of HPV infection to some pathological features in precancerous lesions of the larynx, not examined e xtensively so far. Fifty formalin-fixed paraffin-embedded tissue sections c ontaining human laryngeal precancerous lesions were screened for the presen ce of HPV infection by polymerase chain reaction, and for capsid protein ex pression by immunohistochemistry with polyclonal antibody directed against the L1 protein. The presence of HPV DNA was detected in 28 of 50 specimens (56%), including 9/12 cases with mild dysplasia (75%), 3/6 cases with moder ate dysplasia (50%), and 7/11 cases with severe dysplasia (64%). Multiple H PV infections, containing two or three types, were detected in 17 of the 28 HPV-positive lesions (60%). Of 21 cases with keratosis and no dysplasia, 1 1 were positive for HPV DNA (52%) and 4 showed L1 staining (36%). By contra st, L1 positivity was revealed only in two lesions with moderate dysplasia, confirming that fully productive HPV infection is strictly dependent on ep ithelial differentiation and surface keratinization. The probability that H PV is a cofactor in the malignant progression of these lesions is suggested by the fact that 3/4 patients who developed cancer within 50 months were p ositive for HPV DNA. (C) 1999 Wiley-Liss, Inc.