Porokeratosis Palmaris et Plantaris Disseminata: Report of a Case With Abnormal DNA Ploidy in Lesional Epidermis

Background.— Porokeratosis is believed to be a premalignant condition of the skin. Recent flow cytometric studies showing DNA aneuploidy in the epidermis of some types of porokeratosis support this conclusion. We describe a patient with porokeratosis palmaris et plantaris disseminata in whom abnormal DNA ploidy was found in lesional epidermis with the use of flow cytometry. Observations.— DNA flow cytometry of lesional epidermis from the back showed two populations of cells, one with diploid and the other with aneuploid DNA content and DNA index of 1.1 (hyperdiploid). The coefficient of variation of the diploid and aneuploid peaks was 2.1% and 4.1%, respectively. Conclusions.— Porokeratosis palmaris et plantaris disseminata, like other forms of porokeratosis, exhibits abnormal DNA ploidy in lesional epidermis. This finding underscores the premalignant nature of this and other forms of porokeratosis.