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Back| Classification | Characteristics | |
|---|---|---|
| Gross | Microscopic | |
| Usual Type VIN (VIN, usual type) | Clear boundary of skin lesions | |
| Warty Type VIN (VIN, warty type) | Wart-like appearance | Koilocytes, parakeratosis, and hyperkeratosis cells, thickened spinous layer, significant cellular atypia |
| Basaloid Type VIN (VIN, basaloid type) | Flat hyperplasia or non-papillomatous lesions | Thickened epithelium, numerous proliferating undifferentiated basal-like cells extending upwards from the basal layer, fewer koilocytes than warty type VIN |
| Mixed Type VIN (VIN, mixed (warty/basaloid) type) | Features of both warty and basaloid type VIN | |
| Differentiated Type VIN (VIN, differentiated type) | Not related to HPV infection | |
| Local elevation, ulceration, warty papules, or hyperkeratotic plaques | Well-differentiated cells, atypia confined to the basal layer, basal cell dyskeratosis, keratin formation within rete ridges | |
| Unclassified Type VIN (VIN, unclassified type) | Other VINs that cannot be classified as usual or differentiated type | |
Description
The new definition of VIN in 2004 refers only to high-grade VIN lesions (formerly VIN II and VIN III). VIN is classified into two types based on pathological morphology, biology, and clinical characteristics.
1. Usual Type VIN is associated with high-risk HPV infection, mostly occurring in young women. Over 30% of cases are accompanied by neoplasia in other parts of the lower genital tract (most commonly CIN) and are related to invasive warty and basal cell carcinoma of the vulva. Usual Type VIN includes three subtypes: warty type VIN, basaloid type VIN, and mixed type VIN.
2. Differentiated Type VIN is not related to HPV infection and occurs on the basis of lichen sclerosis. The morphology is mainly ulceration, warty papules, or hyperkeratotic plaques. It mostly occurs in postmenopausal women, often without other site lesions, and is related to keratinizing squamous cell carcinoma of the vulva. Additionally, VIN lesions that cannot be classified into the above two types, such as vulvar Paget's disease, are classified as unclassified type VIN.
