Vulval intraepithelial neoplasia What is vulval intraepithelial neoplasia? (Squamous) vulval (or vulvar) intraepithelial neoplasia is a pre-cancerous skin lesion of any part of the vulva, and was previously known as Bowen disease of the vulva. Vulval intraepithelial neoplasia is often called VIN. How is VIN diagnosed? The clinical appearance of an irregular red, white or pigmented plaque on the vulva may suggest a diagnosis of VIN. Colposcopy (examination using magnification and a special light) may be used to see the extent of the condition. A skin biopsy is required to confirm the diagnosis and identify invasive cancer. Warty lesions in postmenopausal women should undergo biopsy, particularly if they do not resolve with simple treatment. VIN may occur in women of all ages, although currently an increased number of younger women (even teenagers) are presenting with the condition. The average age of women with VIN is 45-50 years. Classification of VIN In 2004, the International Society for the Study of Vulvovaginal Diseases ( ISSVD ) reclassified VIN. They recommended that the term VIN 1, previously used to describe a mild change in the lower epithelial lining, should no longer be used, as these changes have been found to be due to irritation or non-precancerous viral wart infection and often clear up without treatment. The ISSVD recommended that the term VIN should be used for high grade abnormal squamous lesions (these were previously known as VIN 2 and VIN 3). VIN (usual-type or undifferentiated type) can be described by the pathologist as