Anogenital high-grade squamous intraepithelial lesion comorbid with vulvar lichen sclerosus and lichen planus

Objective: The aim of the study was to describe the clinicopathologic features of vulvovaginal or anal high-grade squamous intraepithelial lesion (HSIL) comorbid with lichen sclerosus and/or lichen planus (LS/LP). Methods: The local pathology database identified 37 consecutive cases from 2007 to 2019 of vulvar, vaginal, or anal HSIL among women who had a histopathologic diagnosis of vulvar LS/LP. Cases had p16 and p53 immunoperoxidase stains. Clinical data included age, relative location of HSIL and LS/LP, immune-modifying conditions, tobacco use, treatment type, and follow-up. Histopathologic data included HSIL morphology categorized as warty-basaloid or keratinizing, p16 and p53 patterns within HSIL, and features of LS/LP. Results: The mean age was 69 years with a median follow-up up 42 months. Lichen sclerosus, alone or in combination with LP, was the comorbid dermatosis in 89%. Lichen sclerosus/lichen planus was overlapping or adjacent to HSIL in two-thirds of cases and located separately in the remainder. Rates of tobacco use and immunologic dysfunction were each 40%. In cases of co-located LS and HSIL, sclerosis was absent under the neoplasia in 57%. Twenty-four percent of HSIL cases showed keratinizing morphology; block-positive p16 and suprabasilar-dominant p53 helped distinguish HSIL from human papillomavirus-independent neoplasia. Conclusions: Histopathologic identification of comorbid HSIL and LS/LP may be challenging because of keratinizing morphology and loss of diagnostic features of LS. Clinicopathologic correlation and use of p16 and p53 are essential to achieve an accurate diagnosis and enact disease-specific management plans.