Premalignant and malignant squamous lesions of the vulva

Vulvar premalignant squamous lesions include low- and high-grade intraepithelial neoplasias. High-grade lesions include usual (classic) and differentiated (simplex) vulvar intraepithelial neoplasia (VIN). Usual VIN (uVIN), the most common, is related to human papilloma virus (HPV), occurs in younger patients, and is frequently multifocal. Differentiated VIN (dVIN), less common, is related to lichen sclerosus and other chronic vulvar dermatoses, occurs in older women, and is usually unifocal. Terminology schemes for premalignant lesions are reviewed. Invasive squamous cell carcinoma also occurs in two distinct clinicopathologic settings. Most conventional keratinizing squamous cell carcinomas arise from a background of dVIN and comprise the majority of invasive squamous tumours. Warty and basaloid invasive squamous cell carcinomas likely develop from uVIN and comprise a minority of invasive tumours. Clinical features, microscopic findings, differential diagnoses, immunoprofiles, prognosis and treatment of premalignant and malignant lesions are addressed.