IDIOPATHIC

 

GUTTATE

 

HYPOMELANSOSIS

 

Idiopathic guttate hypomelanosis (IGH) is an acquired leukoderma, characterized by discrete, round or oval porcelainwhite macules of approximately 2- to 5-mm diameter, which increase in number with aging . Any associated hairs often remain pigmented. Lesions are found in a photodistribution and tend to occur in chronically sun-damaged skin. They are often seen pretibially and on the forearms, although they may also arise on other sun-exposed areas including the face, neck, and shoulders. IGH has been hypothesized not to be idiopathic but UV induced, although controversy exists in literature. Another hypothesis suggests that IGH may reflect the normal aging or photoaging process.

Histologically, IGH lesions are characterized by slight basket-weave hyperkeratosis with epidermal atrophy and flattening of the rete pegs. Lesions show a decrease in melanocytes and melanin content of the affected epidermis and pigment granules are irregularly distributed.

A variety of therapies with variable success are described, including cryotherapy, superficial abrasion, topical steroids, and topical retinoids.