Vulvar intraepithelial neoplasia: aspects of the natural history and outcome in 405 women. 
To determine the clinical characteristics, outcome following surgical treatment, and natural history of cases of untreated vulvar intraepithelial neoplasia (VIN).  Four hundred five cases of VIN 2-3 seen between 1962 and 2003 were reviewed.  The mean age of women with VIN decreased from 50.0 years before 1980 to 39.0 in subsequent years.  After treatment of VIN by excision and/or laser vaporization, half the women required at least one further treatment by the 14th year.  It is estimated that 50% of women with positive surgical margins had at least one further treatment within 5 years, but only 15% of women with negative surgical margins required further treatment.  Invasive vulvar, perianal, or urethral carcinoma occurred in 17 (3.8%) women (mean age 42 years) after treatment.  Nine (2%) cases represented treatment failure, with a median treatment-to-invasion interval of 2.4 years.  Eight (1.8%) cases represented new "field" carcinomas, with a median initial treatment-to-invasion interval of 13.5 years.  Ten untreated cases, aged 32-76 years (mean age 55 years), progressed to invasion in 1.1-7.3 years (mean 3.9 years).  Age, previous pelvic radiotherapy, unifocality, immunosuppression, and association with multicentric neoplasia were not risk factors for the development of invasive vulvar carcinoma in this study.  Spontaneous regression of VIN occurred in 47 women (mean age 24.6 years), with a median interval to complete regression of 9.5 months.  Surgically treated VIN has a high rate of recurrence.  Untreated VIN in women over 30 years has an appreciable invasive potential.