Nonsclerotic Lichen Sclerosus of Vulva: A Clinicopathologic Analysis

The International Society of the Study of Vulvovaginal Diseases (ISSVD) recently defined nonsclerotic lichen sclerosus (NSLS) as a scenario wherein the clinical findings are consistent with lichen sclerosus (LS), but no microscopic evidence of dermal sclerosis is found and recognized 4 histologic subcategories. Herein, we present an institutional experience with NSLS, with an emphasis on frequency, application of the ISSVD categories in routine practice, and clinicopathologic correlation. The authors reviewed clinical and pathologic findings for consecutive vulvar biopsies in which LS was a clinical and/or pathologic consideration. Cases were classified as classical/sclerotic LS (CLS), NSLS (per ISSVD criteria), and "unclassified," the latter of which were cases not classifiable as NSLS or CLS, despite a clinical impression or LS or LS being a significant clinical consideration (ie, "clinical LS"). In clinical LS cases, CLS and NSLS were diagnosed histologically in 61% (182/298) and 15% (44/298), respectively, whereas the remainder were histologically unclassified. The latter group was microscopically heterogeneous, devoid of a consistent pathologic profile, and generally showed absence, focality, minimality, ambiguity, or infrequency of features that would have allowed their categorization into one of the NSLS categories. Among the 4 categories for the categorizable NSLS cases, the "lichenoid dermatitis" pattern (61.4%) was the commonest, followed by dermal fibrosis with acanthosis (22.7%), dermal fibrosis without acanthosis (9.1%), and hypertrophic lichenoid dermatitis (6.8%). The clinical response rates to topical therapies for the NSLS and unclassified groups were 71% and 62%, respectively ( P =0.4). Our findings highlight the significance of clinicopathologic correlation in the diagnosis of NSLS. In the setting of clinical LS, some histologic evidence to support that impression is found in most cases when the ISSVD system for diagnosis and classification of biopsies is applied. However, a subset of clinical LS cases are not pathologically classifiable as either CLS or any of the NSLS categories; these display nonspecific histologic features and require future study.