Improvement of Psoriasis of the Scalp With Ketoconazole

To the Editor.—  We have recently proposed that psoriasis is ordinarily the result of the interaction of various microbial products with an abnormally responsive alternative complement pathway.¹Among the microbial products we suggested might play a role in psoriasis was the yeast Malassezia ovalis (Pityrosporum ovale), which is normally present in the scalp and is a potent activator of the alternative complement pathway.The recent availability of ketoconazole has provided us with an opportunity to test our hypothesis. If M ovalis were indeed evoking the development of psoriatic disease of the scalp, it should be possible to treat psoriasis of the scalp successfully with nothing but oral ketoconazole. Ketoconazole has been reported to be effective in the treatment of Pityrosporum folliculitis,² tinea versicolor,³ and P canis-induced dermatitis in two dogs.⁴ Topical econazole nitrate, a related imidazole antibiotic, was reported to be effective in the treatment