Idiopathic eruptive macular pigmentation: report of five patients.

We report the occurrence of idiopathic eruptive macular pigmentation in four children and one adolescent. This condition appears to be a distinct clinicopathologic and histologic entity. It is characterized by asymptomatic, pigmented macules involving the neck, trunk, and proximal limbs. All patients or their families denied the patients' having taken any drug before the eruption. In all of the patients the first sign was a pigmented spot without preceding erythematous, papular, or hypopigmented lesions. Histologic study showed enhanced epidermal basal layer pigmentation with pigmentary incontinence, a mild perivascular lymphohistiocytic infiltrate, and many melanophages in the papillary dermis. Electron microscopy showed an increased number of melanosomes in basal and suprabasal keratinocytes as well as clustered melanosomes in dermal melanophages. Treatment of this asymptomatic condition is unnecessary because spontaneous resolution of the lesions is to be expected within several months to a few years.