Differentiated intraepithelial neoplasia of the vulva.

We present the clinical and pathological findings of 6 women with intraepithelial neoplasia of differentiated or simplex type (DVIN). The mean age was 68 years (range 55-82). One lesion was still in situ, whereas 5 were associated with squamous carcinoma, 4 of well-differentiated keratinizing type and 1 of poorly differentiated spindle-cell type. The invasive depth of the squamous carcinomas ranged from 0.6 to 8 mm and the surgical margins of all of the resection specimens were uninvolved by neoplastic cells. In contrast, DVIN involved the surgical margins in 5 specimens while the remaining specimen had normal surgical margins. In all 6 vulvar specimens, DVIN showed intense immunoreactivity for Ki-67 in the basal and parabasal cells while only 4 specimens showed reactivity for p53. In 5 surgical specimens with DVIN the number of CD1a cells was increased but little if any immunoreactivity could be found amongst the corresponding invasive neoplastic cells. Four squamous carcinomas also showed diffuse p53 reactivity. There was little difference in the pattern of Ki-67 expression between DVIN and squamous carcinoma. For a number of reasons, DVIN present diagnostic difficulty and considerable interobserver variation also exists. Our study suggests that Ki-67 and p16 are useful for distinguishing DVIN and classical VIN 3, whereas p53 and CD1a are useful for distinguishing DVIN and invasive squamous carcinoma. Furthermore, p53 appears to have higher specificity than sensitivity for distinguishing DVIN from normal squamous epithelium.