[Ashy dermatosis (erithema dyschromicum perstans): prospective study of 23 patients].

During the period between january 1984 to july 1987 in the Hospital Unit "Presidente Juárez" ISSSTE, Oaxaca (Mexico), for the first time was given dermatology consult to 2,683 patients among them, 23 who had ashy dermatosis (Erithema dyschromicum perstans), a study was done for the present time and the future of the same, discarding it as possible cause of that nosological entity: treponemal disease, parasitic, infectious, hepatic and renal. It is commented in relation with the ashy dermatosis and lichen planus, the clinicals variants and the possible sun etiology.