Idiopathic eruptive macular pigmentation: report of 10 cases.

Idiopathic eruptive macular pigmentation (IEMP) is a rare disease. IEMP is characterized by asymptomatic, pigmented macules involving the neck, trunk, and proximal extremities. This study describes 10 cases of idiopathic eruptive macular pigmentation seen during a 9-year period at the Asan Medical Center, Seoul, Korea. We present these characteristic consecutive cases to provide more insight into the clinical picture and course of IEMP. Skin lesions of 8 patients were multiple brown macules involving the trunk, face, neck, and extremities. In 2 patients, multiple dark brown macules and patches were noted. The age of onset varied from 1 to 20 years. Tentative diagnoses were usually ashy dermatosis (erythema dyschromicum perstans), fixed drug eruption, or mastocytosis. The history of any erythema and drug medication was absent. Darier's sign was absent. Skin biopsy specimens showed increased pigmentation of the basal layer in an otherwise normal epidermis. Pigmentary incontinence, melanophages, and mild perivascular lymphohistiocytic infiltrate in the papillary dermis were also revealed. Mast cells could not be found. The lesions gradually disappeared during a period of several months to years. The alleged rarity of IEMP may be partially caused by medical unfamiliarity with this entity, despite its clinical and histopathologic characteristic picture. Treatment of IEMP is unnecessary because spontaneous resolution of the lesions can be expected within several months to a few years.