Epithelial vulvar neoplasms and their changing classification

In recent years, there have been many changes in the classification scheme for squamous lesions of the vulva; this is primarily due to the assimilation of new scientific information into the diagnostic terminology. For example, over the past 75 years we have realized that precancerous and cancerous lesions of the vulva may be induced by a variety of preconditions, which are typically divided into human papillomavirus (HPV) and non-HPV precursor lesions. The latter include several dermatoses, especially lichen sclerosus and lichen planus. Additionally, we have learned that HPV on extramucosal and nongenital sites does not have the same malignant potential as on mucosal or genital sites. Because of the frequent changes in nomenclature due to these discoveries, both old and new terms continue to be used in clinical practice; a summary of these terms is provided to help prevent a misunderstanding of their scope and significance. Important points for clinicians and pathologists who are involved in the care of these patients are provided.