A 45-year-old patient complains of a new white spot on the distal leg.

IDIOPATHIC GUTTATE HYPOMELANOSIS

Idiopathic guttate hypomelanosis (IGH) is a benign condition in which small "white freckles" occur on the skin of the arms and legs. There is no relationship to vitiligo. Electron microscopy shows no significant structural abnormality of the melanocytes. Instead, there is a functional defect in the transfer of melanosomes from the melanocyte to the keratinocytes.

• Small, 2-4 mm, white macules develop on the shins and extensor arms of an adult s typical.
• * IGH most commonly occurs on the distal arms and legs.
• Most people over 40 have some IGH and the prevalence increases with age.
• There does appear to be a "hyperkeratotic" variant of IGH. These lesions are scattered, well circumscribed, flat-topped and hypopigmented papules--much like white seborrheic keratoses. Histologically however they merely show a thicker stratum corneum [CED 2013; 38:526].

Treatment

No treatment is needed. Various interventions have been tried with varying success including tip cryotherapy (using a cotton-tipped applicator dipped in liquid nitrogen, not a spray gun), laser, spot peeling with phenol, and miceroneedling with delivery of 5-FU.

RegionalDerm

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