[Idiopathic eruptive macular pigmentation].

Background: Hyperpigmentation can be due to different cause or have no apparent cause.

Case report: A 4 year-old boy was examined because pigmentation had appeared 5 months earlier. The cutaneous lesions were blue-grey, macular (diameter: 2-3 cm), with a predilection for the trunk, the lower part of the neck and the proximal part of the legs. There was no pruritus and the lesions did not urticate when rubbed. Histologically, there was epidermal acanthosis, moderate hyperkeratosis and dermal infiltration with numerous melanophages. The clinical lesions remained stable 6 months later.

Conclusion: The cutaneous manifestations and their course are similar to those of idiopathic macular pigmentation usually reported in adolescents. Ultramicroscopic findings have led some authors to classify it as lichen planus.