Pityriasis amiantacea

Pityriasis amiantacea is a condition in which there is excessive scaling of the scalp. It is not a diagnosis but rather a description of thick silver-yellow scales that are firmly adherent to the scalp and associated hair. The scales may resemble asbestos, giving rise to the term amiantacea, after the French word for asbestos 'amiante'.

Conditions causing pityriasis amiantacea include scalp psoriasis, seborrhoeic eczema, atopic eczema and, less commonly, tinea capitis.

This chapter is set out as follows:

• It is generally seen in children and young adults
• It is more common in females

• Thick silver-yellow scales that are firmly adherent to the scalp and associated hair. The scaling may be localised or generalised depending on the underlying condition and its duration
• It may be complicated by secondary staphylococcal infection, when the skin becomes wet and crusted 
• Temporary hair loss may occur. Permanent hair loss is uncommon 
• If the underlying skin condition is not obvious, the entire skin should be examined to clarify the cause of pityriasis amiantacea, which will then help direct treatment 

• If the skin looks infected send swabs for C&S

• If tinea capitis is suspected send scrapings, along with a small number of hair follicles, for mycology 

Step 1: remove the scale

• Refer to the relevant management sections in Scalp psoriasis - 'shampoo' and 'thick scale'

Step 2: once the scale has been removed treat the underlying cause

• For inflammatory conditions treatment usually involves scalp applications containing steroid preparations
• Antifungal treatment is needed for tinea
• Refer to the related chapters for further information