A common hypertrophic variant of actinic keratosis is presented. Bland cytologic features are dominant, and the pattern varies markedly from that of other actinic keratoses. Histologic and topographic evidence suggests that the hypertrophic changes are induced by the trauma of chronic rubbing. Shallow biopsy may result in misleading microscopic findings with inconclusive or erroneous histologic diagnosis. (J AM ACAD DERMATOL 7:484-489, 1982.)Le texte complet de cet article est disponible en PDF.