Keratin expression in normal vulva, non-neoplastic epithelial disorders, vulvar intraepithelial neoplasia, and invasive squamous cell carcinoma

The expression of AE1, AE2, AE3. and CAM 5.2 antikeratin monoclonal antibodies was investigated in 68 vulvar specimens by an avidin-biotin complex (ABC) method. They included normal vulva (NV. 10). non-neoplastic epithelial disorders (NNED, 31), vulvar intraepithelial neoplasia (VIN, 17), and squamous cell carcinoma (SCC. 10). AEI weakly stained the basal cell layer in NV, exhibited a uniform suprabasal stain in hyperplasia, failed to stain dysplastic areas in VIN I-II, and was patchy and disorganized in VIN III and SCC. AE2 stained the upper third of the epithelium in NV, NNED, and VIN I-II, but it failed to stain VIN III basaloid and SCC; VIN III bowenoid was locally positive. AE3 offered little information, because it stained all lesions: VIN III and SCC. however, exhibited a patchy and disorganized stain. CAM 5.2 was expressed in only half of the cases of VIN III basaloid and in one case each of VIN I-II and SCC. We conclude that keratin expression varies according to the degree of dysplasia: AEI may serve to separate certain cases of NNED from VIN I-II: AE2 and CAM 5.2 are useful to differentiate both histologic types of VIN III. © 1991 International Society of Gynecological Pathologists.