Children and young adults may present with round or oval fine scaling plaques leaving pale marks on the face, neck, and arms; KOH testing helps differentiate this from vitiligo or tinea versicolor. This condition is:

• A. Pityriasis alba
• B. Lichen simplex chronicus
• C. Eczema craquelé
• D. Pityriasis rosea

Answer: (A)

Pityriasis alba is suggested when children or young adults have round or oval patches that are only faintly scaly and pale on the face, neck, and arms. The key feature is fine scaling with hypopigmented patches that often leave lighter marks as they fade. This pattern is commonly seen with dry skin and atopy, and it tends to improve with regular moisturization and gentle skin care.

The negative KOH test helps separate it from tinea versicolor, which would show fungal elements on KOH prep. Vitiligo, on the other hand, presents as completely depigmented patches without scaling, making pityriasis alba the better fit when there is fine scale accompanying pale patches.