Quantitative studies on the reactions of psoriatic epidermis to treatment.

An image-analysing computer has been used to assess the changes in the length of the dermo-epidermal junction and in the epidermal area in histological sections from psoriatic plaques in groups of patients undergoing various treatment regimes. The changes in these two features closely parallel one another, and measurement of the length of the dermo-epidermal junction may be a relatively simple quantitative method of gauging the course of the disease. Topical fluocinolone acetonide produced a greater improvement than did dithranol or coal tar. Variation in the number of epidermal mitotic figures was not a reliable guide to improvement or otherwise in the psoriatic lesion and reappearance of the granular layer can occur independently of any decrease in mitosis.