Porokeratosis has neoplastic clones in the epidermis: microfluorometric analysis of DNA content of epidermal cell nuclei.

Clinical evidence of malignant epithelial tumors developing on the lesions of porokeratosis has accumulated. To determine the cytologic basis for the malignant change of porokeratosis, the nuclear DNA content of epidermal cells from porokeratosis lesions was measured using microfluorometry. A total of 42% of 33 porokeratosis skin lesions in eight of the 16 patients showed DNA polyploidization in the epidermis. Most of the porokeratosis skin lesions, with or without DNA polyploidization, increased cell proportions in the S and G2/M phase range. These findings suggest that porokeratosis is undergoing the neoplastic process, and is the precursor skin manifestation of malignant tumors.