A 77 years old lady presented with excessive dandruff for many years. She enjoys good health all along with no history of drug allergy. She had been seen in general outpatient clinic and prescribed shampoo which was said to be ineffective. Otherwise she has no other skin lesions. On scalp examination, there was thick scales over her scalp like heaps of asbestos (Fig. 1) with no broken hair or underlying erythematous skin lesion. The clinical diagnosis is Pityriasis amiantacea.
Pityriasis amiantacea (resemble asbestos) is a condition in which there is excessive scaling of the scalp. Thick silvery or yellowish scales encircle the hair shafts and may bind down tufts of hair. Pityriasis amiantacea is a reaction pattern and not a specific diagnosis. Common conditions that may present with excessing scalp scaling include scalp psoriasis, seborrheic dermatitis, tinea capitis. Clinically, Pityriasis amiantacea more often affects females than males. The scaling may be localized or generalized depending on the underlying condition and its duration. Skin scraping or plucked hairs for mycology and bacterial culture may be useful. Skin biopsy is usually not necessary. Olive oil may be used to loosen the adherent scales and wash off with shampoos containing salicylic acid, coal tar or Sulphur. The underlying cause should also be treated if there is one e.g. oral antifungal for confirmed tinea capitis or topical steroid for scalp psoriasis.
Figure 1. A heap of whitish small adherent scales over the scalp.
