hypopigmented

Hypopigmented describes patches of skin, hair, or mucosa that appear lighter than surrounding tissue due to reduced melanin production or loss of pigment cells. It is distinct from albinism, which involves a global lack of pigment, and from hyperpigmentation, which is darker pigmentation.

Causes can be congenital or acquired. Congenital examples include ash-leaf spots associated with tuberous sclerosis complex, which are usually small, well-defined patches present from early life. Acquired causes include post-inflammatory hypopigmentation after dermatitis or trauma, pityriasis alba in children, and fungal infections such as tinea versicolor, which can produce light patches.

Pathophysiology varies: some patches arise from reduced melanin synthesis in otherwise normal melanocytes, while others involve loss or decreased density of melanocytes. In certain conditions pigment cells remain but do not function normally. The appearance and evolution depend on the underlying etiology and skin site.

Diagnosis relies on clinical examination and history. A Wood’s lamp examination can help delineate hypopigmented areas, and skin biopsy may be needed to distinguish hypopigmentation from depigmentation or other lesions when results are uncertain.

Management targets the underlying cause and cosmetic concerns. Many post-inflammatory and pityriasis alba patches improve with time and sun protection. Fungal infections respond to antifungal therapy. Congenital hypomelanotic conditions are often not curable; approaches such as camouflage or, in selected cases, laser therapy may be discussed. Regular monitoring is advised if hypopigmented patches are part of a syndromic condition.