Idiopathic Eruptive Macular Pigmentation

Abstract

Idiopathic eruptive macular pigmentation is an uncommon disorder of cutaneous hyperpigmentation of unknown etiology. It affects mainly children and teenagers with both genders equally affected. Asymptomatic brown macules affecting the neck, trunk, and proximal extremities are characteristic with pigmentation in various tones of brown: light dark to dark brown macules. Lesions usually appear abruptly without history of preceding inflammatory lesions or previous drug exposure. The surface of most macules is not different from the uninvolved skin, although some lesions may have a velvety surface. Mucous membranes and nails are spared. A biopsy of a pigmented spot shows an increased number of melanocytes in the basal-cell layer of the epidermis and prominent melanophages in the papillary dermis, without visible basal layer damage or lichenoid inflammatory infiltrate. A mild perivascular, lymphocytic, and histiocytic infiltrates may be present. Differential diagnosis with erythema dyschromicum perstans (EDP) or “ashy” dermatosis which is characterized by a slowly progressive, occasionally pruritic ash-colored hyperpigmentation, mainly in adults, and histologic changes presents basal layer vacuolization and apoptotic bodies. Prognosis is good in all cases. Treatment is unnecessary; in most cases, slow gradual and spontaneous disappearance of the lesions during several months to years is the rule.