Investigation of Human Papillomavirus Infections in Vulvar Intraepithelial Neoplasia by Polymerase Chain Reaction, Chomogenic In Situ Hybridization and Immunohistochemistry.
Juli-Anne Gardner, Kumarasen Cooper, Vanitha Rajendran, Christine S-C Adamson, Mark F Evans. Fletcher Allen Health Care, Burlington; University of Vermont, Burlington
Background: Several studies suggest there are two distinct types of vulvar intraepithelial neoplasia (VIN) that can progress to vulvar squamous cell carcinoma (VSCC): usual VIN (uVIN) is associated with high-risk (hr) human papillomavirus (HPV) infections and lichen sclerosus/differentiated VIN (LS/dVIN) is rarely associated with hrHPV. This study extends the investigation of HPV in these conditions by combining polymerase chain reaction (PCR), chromogenic in situ hybridization (CISH), and p16INK4a and p53 immunohistochemistry (IHC) assays.
Design: Random cases of uVIN (VIN grade II/III, n=50) and LS/dVIN (n=50) were collected from Fletcher Allen Health Care archives. HPV genotyping was performed by PCR using GP5+/GP6+ primers followed by cycle sequencing. CISH was performed using a biotinyl-tyramide-based assay. IHC was performed using a polymer detection system.
Results: HPV was detected by PCR in 48 (96%) uVINs (1 low-risk HPV, 6 hrHPV types) and in 11(22%) LS/dVINs (3 hrHPV types) [P<0.0001]. HPV was detected by CISH in 37 (74%) uVINs and in 0 (0%) LS/dVINs [p<0.0001]. Among the uVIN, 2 samples demonstrated diffuse (episomal HPV) CISH signals only, 19 specimens showed punctate (integrated HPV) and diffuse signals, and 16 cases displayed only punctate signals; the patients with lesions showing only integrated HPV (median age=52) were significantly older than patients with integrated and episomal HPV (median age=35.0) [P=0.008]. p16INK4a IHC was positive in 48 (96%) uVIN: in 19 cases staining was confined to the lower third of the epithelium and in 29 cases staining extended up to the full epithelial thickness; staining was unrelated to CISH staining pattern [P>0.05]. Sporadic basal layer p16INK4a staining was noted in 33 (66%) LS/dVINs. Suprabasal staining for p53 was noted in 26.5% uVIN and p53 basal layer staining was noted in 50% of LS/dVINs. The uVIN patients (median age=48.5) were significantly younger than the LS/dVIN patients (median age=60) [P<0.0001].
Conclusions: These findings support the existence of two distinctive pathways. uVIN is HPV driven and occurs in younger women, whereas LS/dVIN is most likely hrHPV independent and occurs in older women: the CISH and p16 IHC data suggest that hrHPV detectable by PCR in 22% of the LS/dVINs may be incidental to the lesions. The uVIN CISH data indicate that chronic infections may evolve into lesions containing only integrated HPV. p16INK4a and p53 staining may be used qualitatively to distinguish uVIN from LS/dVIN.
Category: Gynecologic & Obstetrics
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 128, Wednesday Morning