Biopsy-verified vulvar lichen sclerosus: Incidence trends 1997-2022 and increased risk of vulvar squamous precancer and squamous cell carcinoma

Population-based data on the epidemiology of vulvar lichen sclerosus (LS) are sparse and only few prospective studies have investigated the malignant potential of the disease. We used the nationwide Danish Pathology Registry to first assess the incidence of biopsy-verified vulvar LS in the period 1997-2022 and second to examine the incidence of vulvar high-grade squamous precancer and squamous cell carcinoma (SCC) in women with biopsy-verified vulvar LS (1978-2019) compared with that expected in the general female population. For the latter aim, we computed standardized incidence ratios (SIRs) with 95% confidence intervals (CIs). During our study period, the age-standardized incidence rate of vulvar LS increased from 5.0 (1997-1998) to 35.7 (2021-2022) per 100,000 person-years. Compared with the general female population, women with biopsy-verified vulvar LS had significantly increased rates of vulvar high-grade squamous precancer (SIR = 8.5; 95% CI: 7.2-10.0) and SCC (SIR = 16.2; 95% CI: 14.2-18.4). The SIRs of vulvar high-grade squamous precancer and SCC did not vary substantially according to length of follow-up. This nationwide and population-based study shows a 7-fold increase in the incidence of biopsy-verified vulvar LS since 1997. Data also show that women with biopsy-verified vulvar LS have 8.5 and 16 times higher than expected incidence of vulvar high-grade squamous precancer and SCC, respectively. The substantially increased incidence of vulvar high-grade squamous precancer and SCC following LS is important in relation to the clinical management and follow-up of LS patients. While vulvar lichen sclerosus (LS) and vulvar squamous cell carcinoma (SCC) are associated, little is known about the risk of vulvar precancerous lesions among women with LS. Here, using data from the Danish Pathology Registry, the authors assessed vulvar LS incidence and malignant potential. From 1997 to 2022, the age-adjusted incidence of biopsy-verified vulvar LS increased seven-fold. Vulvar squamous precancer and vulvar SCC incidence were, respectively, 8.5 and 16 times higher for women with vulvar LS compared to healthy women. Further research is warranted to differentiate true incidence from heightened awareness and increased likelihood to biopsy vulvar lesions. image