PROBABLE NONPAPILLOMAVIRUS ETIOLOGY OF SQUAMOUS-CELL CARCINOMA OF THE VULVA IN OLDER WOMEN - A CLINICOPATHOLOGICAL STUDY USING INSITU HYBRIDIZATION AND POLYMERASE CHAIN-REACTION

A clinical, pathologic, and molecular virologic analysis of 30 cases of invasive squamous cell carcinoma of the vulva was undertaken to investigate the relationship of human papillomavirus (HPV) to this neoplasm. The presence of the virus was detected by the polymerase chain reaction and localized in the tumor and in the adjacent epithelium by in situ hybridization of paraffin sections of vulvectomy specimens. Specimens were examined for nucleic acid sequences of HPVs 6, 11, 16, and 18 were detected by in situ hybridization utilizing S-35-labeled antisense RNA probes and by polymerase chain reaction using HPV type-specific primers for a segment of the E6 gene followed by Southern hybridization of the amplified products. The cases were classified as typical squamous cell carcinoma, basaloid carcinoma, and warty carcinoma. Typical squamous cell carcinoma shows varying degrees of squamous maturation, whereas basaloid carcinoma is characterized by immature basal-type cells showing minimal or no squamous maturation. Warty carcinoma displays an exophytic condylomatous appearance. The squamous cells of this tumor are mature, and many show koilocytotic atypia characterized by a variable degree of nuclear atypia and cytoplasmic vacuolization. The adjacent epithelium was classified as squamous hyperplasia, lichen sclerosus, or vulvar intraepithelial neoplasia (VIN). VIN was subdivided into basaloid or warty VIN using similar criteria as for the invasive carcinomas. Overall, HPV 16 was detected in 11 cases and HPV 18 in two; none of the cases were positive for HPVs 6/11. HPV was detected in four (21%) of 19 squamous cell carcinomas, six (75%) of eight basaloid carcinomas, and three (100%) of three warty carcinomas. The adjacent epithelial lesions also showed a close correlation with the tumor type and presence of HPV. Fourteen (74%) squamous cell carcinomas had adjacent squamous hyperplasia; all of these squamous hyperplasias were negative for HPV. In contrast, seven (87%) of the basaloid carcinomas had adjacent basaloid-VIN and HPV 16 was detected within the VIN in three. Three warty carcinomas (100%) had adjacent warty VIN or basaloid VIN, and HPV was detected within VIN in two. The mean age of women with squamous cell carcinomas was 77 years, for women with basaloid carcinoma 54 years, and for those with warty carcinoma 47 years. The mean age of women with HPV-negative tumors was 77 years compared with 55 years for women with HPV-positive tumors (p < 0.01). Thus, there appears to be a close correlation between the presence of HPV, specific subsets of invasive carcinoma and VIN, and age. These data suggest that vulvar cancer has a diverse etiology which in young women is HPV-related but in older women has little association with HPV.