ACTION OF CHEMOTHERAPEUTIC AGENTS ON PSORIATIC EPIDERMIS

SUMMARY. —Mitotic counts and histological features have been studied in 35 psoriatic patients prior to treatment, and during treatment with topically applied fluocinolone acetonide, methotrexate, dithranol and coal tar. Prior to treatment there was considerable variation in the mitotic counts in the 35 biopsies. The granular layer was absent in 10 biopsy specimens, partially formed in small areas in 21, well formed in most areas in 2, and normal in 2. There was no correlation between the mitotic counts and state of the granular layer. With methotrexate and dithranol treatment the granular layer showed improvement prior to a significant fall in the mitotic counts. With fluocinolone acetonide the improvement in the granular layer appeared at the same time as a significant fall in the mean mitotic count, but the granular layer had completely reformed in 7 of the 9 patients while the mitotic count was still considerably raised compared to uninvolved psoriatic skin. With coal tar the results were not uniform; some patients showed a significant fall in mitotic counts prior to improvement in the granular layer and others first showed improvement in the granular layer. It is suggested that in clearing psoriasis these drugs have an action other than, or in addition to, inhibiting mitosis. Copyright © 1968, Wiley Blackwell. All rights reserved