Human papillomavirus type 16 infection: a morphological spectrum with evidence for late gene expression

Human papillomavirus (HPV) type 16 is a unique strain found almost exclusively in squamous precancerous lesions and invasive carcinomas of the genital tract. A histological and immunohistochemical analysis of 34 cervical biopsies from which HPV 16 was isolated was performed to determine: the morphological spectrum of HPV 16 "infection" and if HPV late genes were expressed in lesions containing this virus. Twenty-eight of thirty-four (82%) biopsy specimens contained areas fulfilling the histological criteria for cervical intraepithelial neoplasia (CIN) (defined as the presence of abnormal mitoses and/or diffuse nuclear atypia in a portion of the biopsy). However, 19 of 28 (68%) CIN lesions also contained focal areas of epithelium indistinguishable from condylomata. Three biopsy specimens each contained condyloma only and normal-appearing squamous epithelium. Three of thirty-one lesions (10%) showed evidence of HPV capsid antigens. The presence of areas of condyloma, as well as capsid antigens, indicates that lesions containing HPV 16 share certain similarities with conventional warts associated with other HPVs. Furthermore, the wide range of morphology in lesions containing HPV 16 suggests that histological or cytological recognition of HPV 16-associated CIN lesions may not always be possible.