217 A Novel Presentation of Recurrent HPV-independent Vulvar Squamous Cell Carcinoma with a New HPV-associated High-grade Squamous Intraepithelial Lesion

Introduction/Objective An estimated 70% of vulvar invasive squamous cell carcinomas (SCC) are HPV-independent, while the remainder are HPV-associated invasive carcinomas which may have adjacent vulvar intraepithelial neoplasia. Methods/Case Report A 74-year-old patient presented with a new vulvar lesion. She had a history of radical vulvectomy for differentiated vulvar intraepithelial neoplasia (dVIN) and HPV-independent SCC, both with aberrant null p53 expression. Pap smears performed between initial diagnosis and this presentation were negative for squamous atypia; HPV co-testing on one specimen was negative. Vulvar biopsy showed recurrent SCC in a background of lichen sclerosus. Repeat vulvectomy demonstrated invasive SCC with adjacent dVIN and a background of lichen sclerosus. Immunohistochemical staining of the SCC and dVIN showed CK17 positivity and aberrant null expression of p53. Near the margin, a cytomorphologically distinct lesion stained block positive for p16 and showed non-aberrant expression of p53. In-situ hybridization for high-risk HPV was positive. This lesion was classified as HSIL (VIN 2). Results NA Conclusion This case is a novel presentation of HSIL with recurrent dVIN and SCC. As HSIL and dVIN can be morphologic mimickers, pathologists need to be vigilant for both lesions. Further study is needed to determine the impact on patient outcomes from developing HSIL after dVIN.