Vulvar intraepithelial neoplasia
Vulvar intraepithelial neoplasia (VIN) is the abnormal maturation of squamous epithelium (dysplasia) confined to the vulvar surface epithelium. Its etiology is linked to human papillomavirus (HPV), usually type 16. VIN may be asymptomatic in some patients. Symptoms often include pruritus or burning, and the lesion may be white, pigmented, or red; flat or raised.
In older females, there is usually a solitary focus and an increased risk for invasive carcinoma. Young females usually have multifocal lesions that may regress. There is a risk for concurrent or subsequent dysplasia of the cervix, vagina, perianal area and anus.
Microscopically, there appears to be a disordered maturation of squamous epithelium, which is rated in 3 grades, similar to cervial neoplasia. Diagnosis is made with an incisional or excisional biopsy and microscopic examination. VIN 3 is pre-malignant, and will progress to invasion if left untreated. Spontaneous regression may occur in some young women with VIN grades 1 or 2.