Nonsclerotic Lichen Sclerosus: Definition of a Concept and Pathologic Description

OBJECTIVE: Nonsclerotic lichen sclerosus (NSLS) refers to the clinicopathologic situation of examination findings consistent with lichen sclerosus (LS) but without dermal sclerosis on microscopy. This review aims to describe the features of NSLS and provide a classification framework. METHODS: The International Society of the Study of Vulvovaginal Diseases tasked the Difficult Pathologic Diagnoses Committee with development of consensus documents for conditions with problematic histopathology. The Difficult Pathologic Diagnoses Committee reviewed the literature on NSLS and formulated descriptions and diagnostic criteria, then approved by the International Society of the Study of Vulvovaginal Diseases membership. RESULTS: Nonsclerotic LS may be categorized into 4 histopathologic subtypes: lichenoid dermatitis, hypertrophic lichenoid dermatitis, dermal fibrosis without acanthosis, and dermal fibrosis with acanthosis. Each has a pathologic differential diagnosis of 1 or more entities, so clinical correlation is required for final diagnosis of LS. There is no evidence to support a reliable association between absent sclerosis and clinical appearance, duration, or oncogenic potential of LS. CONCLUSIONS: Pathologists and clinicians should be familiar with the concept of NSLS and its implications for patient management. Use of the term “early LS” to indicate a lack of sclerosis in presumed LS should be abandoned. Clinical correlation is required to confirm LS from among the differential diagnoses.