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Integumentary system ORGAN SYSTEMS

Pityriasis alba

Common benign disease, characterized by hypopigmented macules or patches on the face, usually seen in children.


Aetiology

  • History of atopy (M/C):
    • Atopic dermatitis
    • Allergic rhinitis
    • Asthma
  • Sun exposure
  • Poor cutaneous hydration
  • Xerosis
  • Mineral deficiencies

Pathophysiology

Histopathology:

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(A) Histologic examination of the hypopigmented patch revealed hyperkeratosis, focal spongiosis in the epidermis and perivascular inflammatory infiltration (H&E, ×200). (B) Irregularly distributed melanocytes were positive for S-100 protein in the basal layer (S-100 protein, ×200). | Lee, D., Kang, J. H., Kim, S. H., Seo, J. K., Sung, H. S., & Hwang, S. W. (2008). A Case of Extensive Pityriasis Alba. Annals of Dermatology, 20(3), 146–148. https://doi.org/10.5021/ad.2008.20.3.146

Clinical features

Asymptomatic (or mildly pruritic), hypopigmented lesions, often on the face.

pityriasis_alba
Pityriasis Alba. | DermNetNZ

Rare variants:

  • Extensive PA:
    • Characterized by widespread, symmetrical, and more persistent involvement of the skin, lesions distributed predominantly on the trunk rather than on the face, a higher female-to-male ratio, and the histologic absence of spongiosis
  • Pigmenting PA:
    • Lesions have a central zone of bluish hyperpigmentation surrounded by a hypopigmented halo.
    • Often associated with dermatophyte infection and are found primarily in darker skin types
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Multiple hypopigmented, non-scaling, and non-coalescing patches with indistinct borders involving the whole body. | Lee, D., Kang, J. H., Kim, S. H., Seo, J. K., Sung, H. S., & Hwang, S. W. (2008). A Case of Extensive Pityriasis Alba. Annals of Dermatology, 20(3), 146–148. https://doi.org/10.5021/ad.2008.20.3.146

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