Hair casts.

The literature on hair casts suggests they are rare even though Kligman intimated in 1957 that in some scalp diseases they might well be common. In this study, casts have been looked for in a group of orthokeratotic and parakeratotic scalp conditions. Hair casts are indeed common in psoriasis, pityriasis amiantacea, pityriasis capitis and seborrhoeic dermatitis. No casts were seen in women with traction hair styles or in those regularly using hair sprays.