Synopsis
Distinguish reversible livedo reticularis from pathological livedo racemosa and retiform infarction, assess perfusion and thrombotic drivers, select deep tissue appropriately, and escalate ischaemia without empirical anticoagulation.
- Physiological livedo reticularis is a regular closed purple network provoked by cold, usually symmetrical on limbs and substantially resolving with warming.
- Livedo racemosa is persistent, irregular, broken and often wider-meshed across limbs, buttocks or trunk; it raises antiphospholipid syndrome, Sneddon syndrome and other systemic vasculopathies.
- Retiform purpura is fixed non-blanching angular or branching ischaemia that progresses towards ulcer or necrosis and indicates occluded or destroyed vessels rather than benign vasospasm.
- In brown or black skin, a network may look violet, blue-grey or dark brown; side lighting, temperature, refill, pain and comparison after warming reduce reliance on redness.
- First-line assessment is warming response plus pulse, perfusion, neurological and whole-skin examination before targeted blood or autoimmune testing.
- Livedoid vasculopathy causes recurrent severe pain, punched-out ankle or foot ulcers and porcelain-white stellate scars with telangiectatic rims through thrombotic small-vessel disease.
- Blue toes with preserved proximal pulses after angiography or anticoagulation can signal cholesterol embolisation, especially when kidney injury, eosinophilia or livedo accompanies them.
- Antiphospholipid antibodies require a compatible clinical event and persistent laboratory positivity at least twelve weeks apart; one low transient result does not diagnose APS.
- Biopsy an active non-necrotic edge deeply enough to include relevant dermal and subcutaneous vessels; the black centre often contains only end-stage infarction.
- Do not start antiplatelet or anticoagulant treatment for colour alone: confirm the mechanism, check bleeding and platelet risk and treat acute occlusion through the appropriate specialist pathway.
Key red flags
Rest pain, tissue coldness, absent pulses, fixed retiform purpura, necrosis, new focal neurology, severe headache, renal injury, fever, shock, thrombocytopenia, pregnancy morbidity with thrombosis or a rapidly ulcerating livedoid pattern requires urgent specialist review.
Fixed angulated non-blanching patches become painful, blistered or black as branching vascular territories lose flow.
Blue or purple toes, livedo, renal deterioration and eosinophilia follow vascular intervention or anticoagulation while proximal pulses may remain palpable.
Investigation priorities
Separate functional vasospasm from fixed ischaemia and identify limb-threatening disease immediately.
Management branches
A net-like purple, grey or brown skin pattern is newly noticed.
- Photograph the distribution with consent before and after safe warming and determine whether the network is regular and closed or broken, fixed and widespread.
- Ask about pain, ulcer, thrombosis, pregnancy morbidity, vascular procedures, kidney disease, fever and neurological symptoms and examine pulses, refill, temperature and sensation.
- Reassure only a completely reversible asymptomatic physiological pattern; persistent racemosa or retiform change receives targeted systemic and vascular assessment.