Erythema dyschromicum perstans (EDP) is a form of acquired dermal macular hyperpigmentation characterised by well-circumscribed round to oval or irregular patches on the face, neck and trunk that are grey in colour. It is a form of acquired dermal macular hyperpigmentation. Erythema dyschromicum perstans is also called ashy dermatosis (of Ramirez), because of its colour.
It can affect people of any age, but appears to be more frequent in young adults. Women are affected more often than men.
The cause of EDP is unknown - suggestions include the effects of : genetic susceptibility, contact allergy to cosmetics and hair dye, toxic effects of chemicals, whipworm infestation, viral infections and the adverse effect of drugs and medications.
Further info DermNetz, NZ