piebaldismo

Piebaldism is a rare congenital pigmentary disorder characterized by stable, non-progressive patches of depigmented skin and hair, most notably a white forelock. The condition arises from a defect in melanocyte development, typically due to loss-of-function mutations in the KIT gene, which encodes a receptor tyrosine kinase essential for the migration and survival of melanocytes during embryogenesis. The depigmented patches are usually present at birth and persist throughout life. The affected skin shows absence or markedly reduced melanocytes, while surrounding skin remains normally pigmented. Hair within the depigmented areas, including the forelock, is often white or grey early in life.

Genetics and inheritance: Piebaldism most commonly follows an autosomal dominant pattern with variable expressivity and penetrance. Many cases are due to inherited KIT mutations, but de novo mutations also occur. The condition does not typically involve systemic abnormalities, and overall health is usually normal aside from pigmentary changes.

Clinical spectrum and diagnosis: The hallmark features are a white forelock and depigmented patches on the central body and limbs. Diagnosis is usually clinical but can be confirmed by genetic testing identifying a KIT mutation. Differential diagnosis includes vitiligo (acquired depigmentation) and other pigmentary disorders; vitiligo tends to be progressive and inflammatory, whereas piebaldism is congenital and stable.

Management and prognosis: There is no cure. Management focuses on cosmetic considerations and sun protection. For stable lesions, surgical options such as autologous melanocyte transplantation or grafting can improve pigment in affected areas. Genetic counseling is recommended due to the autosomal dominant inheritance pattern. The prognosis regarding health is generally favorable, with normal overall development and function.