Pigmented Purpuric Dermatoses
On this page
Direct answer
Pigmented purpuric dermatoses are chronic, non-palpable purpuric eruptions caused by capillaritis, in which extravasated red cells leave haemosiderin in the dermis. They usually affect the lower legs of middle-aged adults and produce orange-brown pigmentation with petechiae. The Schamberg, Majocchi and Gougerot-Blum variants are the recognised forms, and the histology lacks fibrinoid necrosis, which separates them from true vasculitis.
What you must remember
- Non-palpable purpura: petechiae and purpura that do not raise the skin distinguish this group from palpable vasculitis.
- Capillaritis: a red-cell leak from dermal capillaries, with haemosiderin-laden macrophages, is the core mechanism.
- Schamberg disease: progressive yellow-brown patches of petechiae on the legs, often in men.
- Majocchi disease: purpura annularis telangiectodes, with ring-shaped purpura and telangiectasia.
- Gougerot-Blum disease: lichenoid papules on a purpuric background, usually on the legs, and often itchy, though the eczematid-like variant of Doucas and Kapetanakis is the most pruritic.
- Histology: perivascular lymphocytic infiltrate and haemosiderin, without fibrinoid necrosis or leukocytoclasis.
- Differentials: stasis purpura, drug-related purpura and lichen aureus, a solitary coin-like lesion, must be considered.
- Management: reassurance is central, with topical corticosteroids for itchy variants and rutin, ascorbic acid or PUVA tried in persistent cosmetic cases.
Where the exam tries to catch you
Three traps recur, and each one mistakes a benign pigmentary eruption for something more serious.
- Trap: calling the eruption vasculitis because purpura is present. Correct: the lesions are non-palpable and histology shows no fibrinoid necrosis, so capillaritis is the diagnosis.
- Trap: investigating for systemic vasculitis with a full autoimmune panel. Correct: the condition is cutaneous and benign, so a drug history and clinical review usually suffice.
- Trap: confusing haemosiderin-stained lesions with melasma or post-inflammatory pigmentation. Correct: petechiae and purpura distinguish this group, whereas melasma lacks petechiae and follows a facial pattern.
Frequently asked questions
What is the histological hallmark of pigmented purpuric dermatoses?
Pigmented purpuric dermatoses show a perivascular lymphocytic infiltrate, with extravasated red cells and haemosiderin-laden macrophages in the dermis. The absence of fibrinoid necrosis and leukocytoclasis is what separates these eruptions from true vasculitis.
Which pigmented purpuric dermatoses are itchy?
Gougerot-Blum disease, or pigmented purpuric lichenoid dermatitis, is often itchy, but the eczematid-like variant of Doucas and Kapetanakis is the most pruritic and extensive. Gougerot-Blum produces lichenoid papules on a purpuric background, usually on the legs.
How are pigmented purpuric dermatoses treated?
Treatment of pigmented purpuric dermatoses is largely reassuring, since the eruption is benign though chronic. Topical corticosteroids help itchy variants, and rutin, ascorbic acid or PUVA are tried when the cosmetic appearance is a concern.
Which conditions must be excluded before pigmented purpuric dermatoses is diagnosed?
Stasis purpura, drug-induced purpura, lichen aureus and true vasculitis must be considered before pigmented purpuric dermatoses is diagnosed. Stasis purpura is linked with venous insufficiency and typically sits around the ankles rather than spreading over the shins.