This low power magnification of a biopsy of an ill-defined gray plaque on the perineum shows changes typical of vulvar intraepithelial neoplasia.
There is epidermal thickening with parakeratosis. The suprabasilar keratinocytes possess abundant eosinophilic cytoplasm and occasional vesicular nuclei. The basal cells have hyperchromatic and variably atypical nuclei. Simplex (or differentiated) VIN (vulvar intraepithelial neoplasia), a distinct clinicopathologic subtype, is typically HPV ( Human papillomavirus) negative and arises in older women often in conjunction with lichen sclerosus or lichen simplex chronicus. It is associated with a higher risk of progression to invasive squamous cell carcinoma.