The current classification for VIN was developed in 2004 by the Vulvar Oncology Subcommittee of the International Society for the Study of Vulvar Diseases (ISSVD).
Differentiated VIN (VIN simplex) classification:
- unifocal and unicentric
- not graded
- high risk of developing squamous cell carcinoma (SCC)
- postmenopausal women
- associated with lichen sclerosis and usually have a nonviral etiology
- not classically associated with CIN.
Usual type (VIN is basaloid, warty and mixed) classification:
- multifocal and multicentric
- graded the same as CIN
- low risk of developing SCC
- premenopausal women
- associated with HPV, smoking and immunodeficiency
- may have similar pathophysiology to CIN.