Pityriasis amiantacea is characterized by thick adherent scales that surround the proximal hair shafts of scalp hair. Scales may be white, silvery, gray, or yellow-gray and resemble asbestos. The condition is usually seen in children and young adults and may be more common in females than males. There is no racial or ethnic predilection.

May be localized or generalized. May be an isolated finding or it may occur in association with inflammatory conditions of the scalp. Of these, psoriasis and seborrheic dermatitis are most commonly seen. Other associated conditions include atopic dermatitis and tinea capitis (reported in 11 of 85 patients in one study).