The most important prognostic factor in vulvar cancer is inguinal lymph node status at the time of diagnosis, even in locally advanced vulvar tumors. The aim of our study was to identify the risk factors of lymph node involvement in these women, especially the impact of lichen sclerosis (LS). We conducted a retrospective population-based cross-sectional study in two French referral gynecologic oncology institutions. We included all women diagnosed with a primary invasive vulvar cancer. Epithelial alteration adjacent to the invasive carcinoma was found in 96.8% ( = 395). The most frequently associated was LS in 27.7% ( = 113). In univariate analysis, LS ( = 0.009); usual type VIN ( = 0.04); tumor size >2 cm and/or local extension to vagina, urethra or anus ( < 0.01), positive margins ( < 0.01), thickness ( < 0.01) and lymphovascular space invasion (LVSI) ( < 0.01) were significantly associated with lymph node involvement. In multivariate analysis, only LS (OR 2.3, 95% CI [1.2-4.3]) and LVSI (OR 5.6, 95% CI [1.7-18.6]) remained significantly associated with positive lymph node. LS was significantly associated with older patients ( = 0.005), anterior localization ( = 0.017) and local extension (tumor size > 2 cm: = 0.001). LS surrounding vulvar cancer is an independent factor of lymph node involvement, with local extension and LVSI.