Schamberg's disease (syn. Progressive Pigmented Purpuric Dermatosis) is characterized by the ongoing eruption of clusters of purpuric puncta and by the subsequent formation of pigmented orange to brown patches due to hemosiderin deposition. The patches are generally asymptomatic and localized on the lower limbs but may occur anywhere on the body. Histological examination shows a lymphocytic vasculitis involving the blood vessels of the upper dermis (i.e. mainly the capillaries) with endothelial swelling, extravasated red blood cells, and a perivascular lympho-monocytic inflammatory infiltrate.
The aetiology is still unknown and more than half of the patients have no clinical or laboratory evidence of associated systemic disease. Nontheless purpura simplex has been described in patients with lupus erythematosus or rheumatoid arthritis. In a report on 118 patients with rheumatoid arthritis, 7 cases of purpura simplex were observed, none of which had any clinical evidence of systemic vasculitis or had received any new medication before the onset of the capillaritis.