Epidermal thickness and skin appendage involvement in vulvar intraepithelial neoplasia.

Colposcopically directed biopsies obtained from 165 women with vulvar intraepithelial neoplasia (VIN) were studied to determine both the thickness of the dysplastic epithelium and the depth of involved and noninvolved skin appendages and ultimately to provide a morphometric basis for laser therapy for the condition. Multiple measurements per section were made, and the mean epithelial thickness was calculated for each biopsy. The mean (+/- SD) thickness of the epithelium for all grades of VIN was 0.52 +/- 0.23 mm, with the lesions ranging in thickness from 0.10 to 1.90 mm. The thickness of the involved epithelium varied little, regardless of the location of the lesions. The study indicated that VIN frequently is a multifocal disease most commonly affecting the central vulvar structures, with the posterior half of the vulva the area affected most often. The difference in thickness between the various grades of VIN was not of practical clinical significance from a therapeutic point of view. The measurements suggest that laser vaporization to a depth of 1.0 mm, including the zone of thermal necrosis, should be sufficient to destroy most epidermal lesions without skin appendage involvement. If the initial biopsy showed involvement of adjacent hair follicles or sebaceous glands, deeper tissue destruction would be necessary to theoretically achieve greater than 90% elimination of the disease.