Rarely, the disease may be quite extensive. Extensive PA presents with numerous lesions on the trunk and extremities. This form of PA generally occurs in older patients and the lesions may be more persistent. Important aspects of examination Examine for keratotic lesions on the elbows and knees and for small pits in the nails, which may suggest a diagnosis of psoriasis. Excessively dry skin, which is frequently exacerbated by cold, dry environments, appears to be a common factor.
Lesions are visible primarily in contrast to dark skin.
Increasing sunlight in spring and summer makes them more apparent. The condition is not contagious and no infectious agent has been identified. Any inflammatory process involving the skin, such as contact dermatitis, can leave areas of hypopigmentation upon healing. Hypopigmentation may also result as a side effect of medications such as retinoic acid, benzoyl peroxide, and topical steroids. The most common disorders of hypopigmentation in children are PA, vitiligo, nevus depigmentosus, and tinea versicolor.