Localised histiocytic lipofuscinosis. An unusual pigmented lesion

We report a case in an 86-year-old woman, of a localised aggregate of lipofuscin-laden histiocytes presenting as a pigmented lesion with local itching. Histologically, there was a diffuse dermal infiltrate of mononuclear cells, predominantly histiocytes containing golden-brown pigment shown to be lipofuscin. The typical ultrastructural appearance of this pigment was demonstrated on electron microscopy, and adjacent iron deposition was confirmed. The etiology of this rare lesion is unclear. Clinical distinction from pigmented cutaneous malignancies may be difficult.