Electron microscopic assessment of cervical punch biopsies in women followed-up for human papillomavirus (HPV) lesions.

Cervical punch biopsies from 102 women prospectively followed-up for HPV (Human papillomavirus) lesions (flat, inverted and papillomatous condylomas) were assessed on transmission electron microscopy (TEM) for the presence of HPV particles. The virus discovery rate was correlated with the other characteristics of significance to the clinical behaviour (natural history) of these lesions, i.e. the colposcopic pattern, expression of papillomavirus genus specific structural antigens (demonstrated by an indirect immunoperoxidase, IP-PAP technique), as well as the degree of HPV-associated cervical intraepithelial neoplasia (CIN). Virus particles were disclosed with equal frequency in all three types of HPV lesions. Noteworthy, and so far unreported, was the discovery of HPV particles in 56 and 64% of the biopsies derived from the epithelium without colposcopic or histological evidence (cytopathic effects) of HPV lesions, respectively. The degree of CIN was without influence on the virus discovery rates. Viral particles were present with equal frequency (57 and 60%, respectively) in the lesions expressing HPV antigens and in those which did not. The highest frequency (89%) of viral particles was found in lesions presented with warty or mosaicism pattern in colposcopy. The implications of these findings to understanding the biology of HPV infections in the uterine cervix is discussed, and the importance of TEM in the follow-up of these lesions is emphasized.