Purpuric generalized lichen nitidus: an unusual eruption simulating pigmented purpuric dermatosis.

BACKGROUND: Generalized haemorrhagic lichen nitidus is rare. To our knowledge, this form of presentation has only been reported once.

OBJECTIVE: To describe a new case of generalized haemorrhagic lichen nitidus simulating a pigmented purpuric dermatosis.

METHODS AND RESULTS: We document a 24-year-old man who presented with an 8-month history of a progressive non-pruritic, red-brown papular eruption on the dorsa of the feet, ankles and distal third of the legs. A diagnosis of Schamberg's progressive pigmentary dermatosis was made, and no treatment was prescribed. Two months later, the lesions had extended to the abdomen, groins, forearms, elbows and wrists. Biopsy of the skin of the right foot revealed lesions typical of lichen nitidus with subepidermal extravasation of red cells and capillary wall hyalinization. Macrophages and T lymphocytes were abundant in the infiltrate.

CONCLUSION: Purpuric generalized lichen nitidus should be included in the differential diagnosis of pigmented purpuric dermatoses.