Comprehensive analysis of 130 multicentric intraepithelial female lower genital tract lesions by HPV typing and p16 expression profile

Abstract

Purpose: HPV associated cervical transformation is characterized by well-defined steps, including persistent HPV infection and deregulated oncogene expression. Recent studies have suggested that a number of lower genital tract lesions are clonally related to cervical lesions. In the current study, HPV infections and oncogene expression were assessed in a large series of patients with multicentric lower genital tract disease to analyze the transformation steps in extracervical disease.

Methods: One hundred and thirty biopsies of 52 women treated for multicentric synchronous or metachronous lower genital tract intraepithelial neoplasias were collected. Up to seven multicentric specimens taken from one patient were studied with a maximum follow up of 20 years. HPV typing and p16(ink4a) immunostaining was performed.

Results: HPV DNA was present in 121 of 130 specimens (93%). HPV16 was frequently found in VIN, VaIN and AIN (73, 60 and 77%, respectively), whereas only 37% of CIN were HPV16 positive. Infections with identical HPV types in multicentric lesions were diagnosed in 46% of the HPV positive patients. p16INK4a expression was negative in the nine HPV negative lesions whereas about 90% of the high grade lesions showed diffuse p16 staining.

Conclusion: Our findings indicate that multicentric lower genital tract disease evolves through different pathways. Some cases were related to a high susceptibility towards HPV infections, while others exhibited features of clonal propagation of transformed cervical cell clones. The clinical management of the latter group is particularly challenging, because malignant cell clones can persist over a long time course.

Fig. 1

Percentage of HPV DNA prevalence (first bar), infection with high-risk (second bar) and low-risk (third bar) HPV types and double infections (fourth bar), respectively, in 30 CIN, 21 VaIN, 53 VIN and 26 AIN lesions

Fig. 2

Distribution (in percent) of the most common HPV subtypes in 130 preneoplastic lesions of different locations (CIN first lane; VaIN second lane; VIN third lane; AIN last lane): HPV 16 first row; HPV 18 second row; HPV 31 third row, HPV 33 fourth row, low risk types fifth row, rare HPV types and types with unknown risk are summarized in the last row

Fig. 3

p16INK4a staining of three representative cases with multicentric lower genital tract disease: Case one with evidence for persisting transformed cell clones (ID 25): a Diffuse p16INK4a positive VIN3 lesion at age 37, 22 months after CIN3 lesion, b diffuse p16INK4a positive VIN3 lesion 22 months after CIN3 lesion, c Diffuse p16INK4a positive AIN3 lesion 22 months after CIN3 lesion. All lesions were HPV16 positive. Case two with evidence for persisting transformed cell clones (ID 27): d diffuse p16INK4a positive VIN2 lesion at age 39, 26 months after initial CIN2 lesion (n.a.). e Diffuse p16INK4a positive AIN2 lesion at the same time, f diffuse p16INK4a positive VIN3 lesion 38 months after initial CIN2 lesion. All lesions were HPV16 positive. Case three with susceptibility to uncommon HPV infections (ID 36): g diffuse p16INK4a positive VIN3 lesion at age 37, HPV58 positive, h p16INK4a negative VAIN1 lesion, HPV42 positive at the same time

Fig. 4

Schematic presentation of three hypothetic concepts of pathogenetic mechanisms leading to the development of multicentric intraepithelial lesions in the lower genital tract. Model 1 (a): Field effect of a transforming agent that induces independently transformed cell clones, characterized by synchronous lesions, identical (HR-)HPV type and various levels of oncogene expression. Model 2 (b): Increased susceptibility to HPV infection and transformation characterized by repeated infections with various HPV types, including lesions positive for uncommon types and frequently deregulated oncogene expression. Model 3 (c): Clonally related lesions, characterized by previous cervical lesion, metachronous lesions, sometimes over a long time course, identical HPV type in all metachronous lesions and aberrant oncogene expression