If your cat has what looks like coffee grinds all over his chin, corners of mouth, in the crease just below the eyes, it IS the idiopathic dermatis that biemme spoke about. Our Raven(a Persian), has it. We " wash " her face after each meal(twice a day). I have found that using a flea comb helps remove the debris. I have read that drugs are ineffective in treating it. Tresaderm does not even help!!! Good luck!!!