Cytology of the exfoliative layer in normal and diseased vulvar skin: correlation with histology.

The vulvae of 464 patients were studied by cytologic and/or histologic examination. Of these, 286 patients had clinically normal vulvae and 178 patients, diseased vulvae. Histology revealed 47 benign, 20 precancerous and 111 malignant lesions. Structural variations of the vulvar stratum corneum could be classified into five categories: orthokeratosis, hyperkeratosis, parakeratosis, dyskeratosis and tumor penetration. Orthokeratosis, hyperkeratosis and parakeratosis were present in the normal vulvae as well as in benign conditions; they were characterized cytologically by anucleated horny squames or by parakeratotic cells. Dyskeratosis usually indicated precancerous or malignant conditions but was also observed, although in mild form only, in certain benign lesions, e.g., acute inflammation and condyloma acuminatum. Nevertheless, evidence of dyskeratotic cells in vulvar smears should cause concern because vulvar cancer frequently is covered by a continuous horny (dyskeratotic) layer. Only half of the malignant vulvar lesions showed tumor penetration through this superficial layer, with subsequent exfoliation of tumor cells.