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Pityriasis amiantacea in Adult
Other Resources UpToDate PubMed

Pityriasis amiantacea in Adult

Contributors: Susan Burgin MD, Lowell A. Goldsmith MD, MPH
Other Resources UpToDate PubMed


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).


L44.8 – Other specified papulosquamous disorders

238924007 – Pityriasis amiantacea

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Psoriasis
  • Seborrheic dermatitis
  • Atopic dermatitis
  • Tinea capitis
Other concretions around the hair shaft:
  • White piedra – many soft, fluffy white or light brown nodules are seen; more commonly affects pubic hair, axillary hair, beard and mustache area. Scalp is occasionally involved.
  • Black piedra – usually affects scalp hair. Small compact black nodular concretions, often multiple on one hair, are seen.
  • Trichomycosis axillaris – long, thin yellow or orange concretions may spiral around hair shafts of axillary or pubic hair.
  • Pediculosis capitis – nits adhere to the proximal portions of affected hair. They are small and white. Associated adult lice attach to any portion of the hair shaft.

Best Tests

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Management Pearls

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Updated:06/21/2022
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Pityriasis amiantacea in Adult
A medical illustration showing key findings of Pityriasis amiantacea : Concretions on hair, Scaly plaque
Clinical image of Pityriasis amiantacea - imageId=3022928. Click to open in gallery.  caption: 'Thick, adherent scales on the scalp and around the hair shafts.'
Thick, adherent scales on the scalp and around the hair shafts.
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