depigmentation

Depigmentation refers to partial or complete loss of pigment in the skin, hair, or mucous membranes due to disruption of melanin production or melanocyte survival. It can be acquired or congenital and may present as focal patches or diffuse whitening.

Causes and mechanisms include loss of melanocytes, reduced melanin production, or altered distribution of pigment. The best-known acquired example is vitiligo, in which autoimmune destruction of melanocytes leads to well-demarcated, depigmented patches. Other acquired forms include post-inflammatory depigmentation after inflammation or injury, chemical depigmentation from agents such as hydroquinone or phenols, and pigmentary changes from infections like tinea versicolor. Congenital causes include albinism, due to defects in melanin production, often tyrosinase deficiency, and piebaldism, which features congenital depigmented patches.

Diagnosis relies on clinical examination and history, with auxiliary tests as needed. Wood’s lamp examination helps distinguish depigmented patches (often bright white) from hypopigmented areas. Skin biopsy can show absence of melanocytes in vitiligo-affected skin, whereas albinism shows normal melanocyte numbers with reduced melanin production. Other conditions in the differential include fungal infections and post-inflammatory changes.

Treatment and prognosis depend on the underlying cause and cosmetic concerns. For vitiligo, options include topical corticosteroids or calcineurin inhibitors, phototherapy (narrow-band UVB, PUVA), and surgical approaches such as melanocyte transplantation for stable disease; depigmentation of remaining pigmented skin with agents like monobenzone is an option in extensive, widespread vitiligo. Cosmetic camouflage and sun protection are commonly used. Post-inflammatory depigmentation may gradually repigment or persist. Albinism requires sun protection and management of vision problems; there is no cure to restore normal melanin production.