Areas shaded by the chin usually are spared. Chronic exposure to ultraviolet light appears to be a primary etiologic factor, which is supported by the finding that lesions occur on sun-exposed areas. In addition, solar elastosis is a frequent histopathologic finding. Photosensitizing chemicals in perfumes or cosmetics have been implicated in the pathogenesis of poikiloderma of Civatte. Possibly, hormonal changes related to menopause or low estrogen levels may be a factor.
Most patients are middle-aged or elderly women.
Genetic predisposition may exist. This is supported by the presence of the condition in successive generations, and in individuals of both sexes, consistent with an autosomal dominant inheritance with variable penetrance. The genetically determined predisposition may be expressed as an increased susceptibility of the skin to ultraviolet radiation. The epidermis shows moderate thinning of the stratum malpighii, hydropic degeneration of the basal cells, and effacement of the rete ridges. In the upper dermis, a bandlike inflammatory infiltrate primarily is composed of lymphocytes with few histiocytes, in addition to pigment incontinence.