Pagetoid dyskeratosis of the lips

Pagetoid dyskeratosis is an incidental finding in a variety of lesions of t he skin and squamous mucosa. The lesion is considered a selective keratinoc ytic response in which a small part of the normal population of keratinocyt es is induced to proliferate in response to friction. As far as we know, pa getoid dyskeratosis has not been reported in the lips. In this article, we describe the location of the lesion in the lips and its incidence in a grou p of 90 unselected patients who underwent biopsy or were surgically treated for diverse labial lesions. Histochemical staining and immunohistochemical studies were performed in selected cases. Pagetoid dyskeratosis was found in 38 cases (42.2%) but only in 6 cases (6.7%) the lesion was conspicuous. There was no significant difference between the upper and the lower lip in terms of incidence of the lesion. Labial pagetoid dyskeratosis was more fre quent in younger patients (46.7 +/- 25.0 versus 58.5 +/- 20.5; p < 0.05) an d in women (<chi>(2) = 3.89; p < 0.05). Pagetoid cells were more common in suprabasal location and in the labial mucosa. These cells showed positivity for hi-h-molecular weight cytokeratin and negative reaction for low-molecu lar weight cytokeratin, epithelial membrane antigen, carcinoembryonic antig en, and human papilloma virus. The immunohistochemical profile is different from the surrounding keratinocytes, indicating premature keratinization. T he main differential diagnoses include white sponge nevus, leukoedema, oral koilocytoses, hairy leukoplakia, pagetoid squamous cell carcinoma in situ, and extramammary Pa-et's disease of the oral mucosa. The morphologic featu res of dyskeratotic pagetoid cells are distinctive and easily recognized as an incidental finding, thus preventing confusion with other important enti ties including an intraepidermal tumor.