Idiopathic eruptive macular pigmentation

A 23‐year‐old, dark‐skinned man presented at the dermatology department with pigmented macules over the trunk and proximal thighs of 2 months’ duration. He reported that the number of lesions had increased progressively for a few weeks and then remained stable. Skin examination showed oval brown macules and patches, 5–40 mm in diameter, involving mainly the anterior trunk and proximal thigh, but also the neck and dorsum ( Fig. 1 ). The lesions were asymptomatic. There was no previous history of an inflammatory process, erythema, scaling, or drug intake. The mucous membranes, palms, and soles were clear. The pigmentation was not influenced by sunlight. Darier's sign (urticaria or erythema around the macules after scratching or rubbing of the lesions) was absent. The previous use of emollients, keratolytics, and topical antifungal agents did not alter the aspect of the lesions. The results of physical examination and routine laboratory tests (blood cell count, blood chemistry) were normal. Venereal Disease Research Laboratory (VDRL) test and direct skin examination and culture for fungus were negative. A biopsy specimen was obtained from a pigmented macule. The histologic study showed hyperkeratosis and acanthosis, epidermal basal layer pigmentation with an irregular distribution, focal mild lymphohistiocytic infiltrate in the papillary dermis and dermal–epidermal junction, and discrete pigmentary incontinence ( Figs 2–4 ). The mast cell population was normal. A further biopsy 1 year later showed similar findings.

Figure 1 Open in figure viewer PowerPoint Multiple brown macules involving the trunk