Livedo reticularis and thrombotic skin disease

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Livedo describes a violaceous net created by uneven flow and oxygen extraction around the cutaneous vascular cones. A fine complete lattice after cold exposure can be physiological, particularly in younger people, and should fade with warmth. Persistence, pain, asymmetry, a broken irregular network or extension to trunk and buttocks changes the pre-test probability. Livedo racemosa is a descriptive warning pattern rather than a diagnosis and may reflect antiphospholipid disease, Sneddon syndrome, connective-tissue disease, emboli, hyperviscosity, medicine effects or other occlusive states.

Retiform purpura is further along the ischaemic pathway. Its angulated non-blanching branches represent infarcted territories downstream of blocked or inflamed vessels. Assess pulse, temperature, refill and sensation immediately and ask about sudden onset, vascular procedures, dialysis, warfarin, pregnancy loss, thrombosis, migraine or stroke, infection, cold exposure, medicines and systemic symptoms. Livedoid vasculopathy is a chronic recurrent cutaneous thrombotic syndrome with intense pain, small ulcers around ankles and feet and stellate white scars, not simply another name for livedo reticularis.

Investigation is hypothesis-led. Platelets and coagulation distinguish consumption and bleeding; renal function and urinalysis identify systemic injury; APS, cryoglobulin and paraprotein testing require correct timing and handling. Vascular imaging answers macrovascular disease, while a deep edge biopsy distinguishes thrombotic vasculopathy, vasculitis, calcification, cholesterol clefts and other vessel pathology. Because many prothrombotic results are affected by acute illness or anticoagulants, interpretation with haematology is safer than a large untimed panel.

Key points

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.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Physiological vasospasm

Cold constricts dermal arterioles unevenly and pools deoxygenated blood in venous plexuses, producing a reversible regular network without structural vessel damage.

Autoimmune thrombosis

Antiphospholipid antibodies and related endothelial or platelet activation promote arterial, venous and microvascular clotting and pregnancy morbidity in a susceptible phenotype.

Embolic and clonal disease

Cholesterol crystals, cardiac emboli, paraprotein, myeloproliferation and hyperviscosity obstruct cutaneous vessels and may simultaneously injure kidney, brain or bowel.

Inflammatory or calcific occlusion

Vasculitis, cryoproteins, infection and calciphylaxis damage or block vessels, turning a livedoid network into fixed purpura, ulceration and necrosis.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Flow outlines vascular cones
Each cutaneous arteriole supplies a central pale field surrounded by visible venous channels, making reduced inflow or slow outflow appear net-like.
2
Thrombi create broken territories
Segmental luminal obstruction produces irregular incomplete arcs and, when severe, angulated zones of infarction rather than a uniform cold lattice.
3
Microemboli spare large pulses
Small cholesterol crystals or thrombi lodge downstream while conduit arteries remain patent, preserving palpable pulses despite painful cyanotic digits.
4
Repeated ankle thrombosis scars
Livedoid vasculopathy repeatedly occludes superficial vessels, causing painful focal necrosis that heals with stellate porcelain-white fibrosis and surrounding telangiectasia.
5
Inflammation can mimic occlusion
Destructive vasculitis narrows and ruptures vessels secondarily, so histology must distinguish primary wall inflammation from bland intraluminal thrombosis.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Cold-responsive regular net

A fine symmetric unbroken lattice on limbs fades after warming and lacks pain, ulceration, neurological symptoms or systemic illness.

Persistent livedo racemosa

A coarse broken irregular network remains warm and extends beyond distal limbs, prompting assessment for APS, Sneddon and systemic vascular disease.

Retiform infarctionRed flag

Fixed angulated non-blanching patches become painful, blistered or black as branching vascular territories lose flow.

Livedoid vasculopathy

Recurrent burning pain precedes small punched-out lower-leg ulcers that heal with porcelain-white stellate atrophie-blanche scars and peripheral telangiectasia.

Cholesterol embolic patternRed flag

Blue or purple toes, livedo, renal deterioration and eosinophilia follow vascular intervention or anticoagulation while proximal pulses may remain palpable.

Sneddon phenotype

Widespread persistent racemosa with transient ischaemic attacks, stroke, cognitive change or severe headaches suggests a neurocutaneous arteriopathy.

Inflammatory vessel pattern

Palpable purpura, nodules, systemic inflammation, haematuria or neuropathy makes vasculitis more likely than a purely thrombotic livedoid process.

Red flags requiring action

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.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Warmth and full vascular examinationFirst step
Why
Separate functional vasospasm from fixed ischaemia and identify limb-threatening disease immediately.
Interpretation and limitations
Document network before and after controlled warming and examine pulses, refill, temperature, sensation and motor function; persistent pain or loss overrides a cosmetic interpretation.
02
FBC, film and coagulation
Why
Detect platelet consumption, thrombotic microangiopathy, myeloproliferation, DIC and bleeding risk before antithrombotic treatment.
Interpretation and limitations
Schistocytes with anaemia, thrombocytopenia and organ injury is an emergency; a high haematocrit or platelet count may direct clonal testing, while normal PT does not exclude thrombosis.
03
Renal, liver, CRP and urine tests
Why
Find systemic inflammation, embolic renal injury, liver-related coagulation change and glomerular disease.
Interpretation and limitations
A creatinine rise and eosinophilia after angiography supports cholesterol embolisation; haematuria with casts may favour inflammatory vessel disease.
04
Antiphospholipid antibody panel
Why
Assess thrombotic or pregnancy-morbidity phenotypes for APS using interpretable timing.
Interpretation and limitations
Test lupus anticoagulant, anticardiolipin and anti-beta-2-glycoprotein I with specialist awareness of anticoagulant interference; criteria require persistent positivity at least twelve weeks apart.
05
Cryoglobulin and protein studies
Why
Detect temperature-dependent protein precipitation, paraprotein and hyperviscosity when cold, purpuric or systemic clues support them.
Interpretation and limitations
Keep cryoglobulin blood warm through clotting and serum separation; add immunoglobulins, electrophoresis and immunofixation and interpret a negative mishandled sample cautiously.
06
Arterial and venous imaging
Why
Map macrovascular occlusion, embolic source or venous thrombosis when examination or history indicates it.
Interpretation and limitations
Use Doppler pressure and duplex first where suitable, escalating to CT, MR or catheter angiography for threatened tissue and intervention planning.
07
Deep active-edge biopsy
Why
Differentiate thrombotic vasculopathy, vasculitis, cholesterol emboli, calciphylaxis and occlusive infection.
Interpretation and limitations
Sample the viable advancing margin and enough subcutis, potentially at more than one site; end-stage black centre often lacks the causal vessel and biopsy itself carries healing risk.
08
Neurological and cardiac assessment
Why
Investigate livedo racemosa with TIA, stroke, migraine-like symptoms or embolic concern.
Interpretation and limitations
Brain MRI, vascular imaging, ECG monitoring and echocardiography follow the clinical syndrome; normal skin biopsy cannot exclude cerebral or cardiac disease.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Physiological livedo

A regular symmetric pattern that vanishes with warmth and lacks pain, ulcers or systemic events is a benign functional response.

Cutaneous vasculitis

Raised purpura, nodules, inflammatory ulceration, renal findings and leukocytoclastic or medium-vessel wall injury support primary inflammation rather than bland thrombosis.

Calciphylaxis

Extreme pain, woody induration and retiform necrosis in advanced kidney disease or a high-risk non-uraemic setting demands urgent calcific-arteriolopathy care.

Cholesterol embolisation

Blue toes, livedo, eosinophilia and renal decline after arterial instrumentation or anticoagulation with retained pulses suggests crystal showering.

Cold protein disease

Cold-associated purpura, acrocyanosis, neuropathy, renal disease or hyperviscosity raises cryoglobulin, cryofibrinogen or cold-agglutinin pathology requiring meticulous sampling.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01First-line pattern sequenceWarm, map and test perfusionFirst stepFirst lineA net-like purple, grey or brown skin pattern is newly noticed.

1Photograph the distribution with consent before and after safe warming and determine whether the network is regular and closed or broken, fixed and widespread.
2Ask about pain, ulcer, thrombosis, pregnancy morbidity, vascular procedures, kidney disease, fever and neurological symptoms and examine pulses, refill, temperature and sensation.
3Reassure only a completely reversible asymptomatic physiological pattern; persistent racemosa or retiform change receives targeted systemic and vascular assessment.

02Acute ischaemia routeProtect tissue before aetiological completenessSkin is cold, severely painful, pulseless, neurologically impaired or progressing to fixed retiform necrosis.

1Activate emergency vascular assessment, keep the limb uncompressed and protect it from trauma and cold while providing analgesia and ABCDE support.
2Obtain FBC, coagulation, renal and liver profiles, lactate and urgent vascular imaging without delaying time-critical revascularisation or sepsis treatment.
3Add haematology, renal, infection or dermatology expertise as DIC, TTP, calciphylaxis, cholesterol emboli or inflammatory occlusion becomes plausible.

03Persistent racemosa routeLink skin network to brain and pregnancy historyA broken warm-resistant livedoid pattern persists without immediate limb threat.

1Screen for TIA, stroke, severe headache, cognitive change, thrombosis, miscarriage, autoimmune symptoms, medicines and vascular risk and perform neurological and cardiovascular examination.
2Request FBC, renal, liver and urine testing and select APS, autoimmune, cryoprotein, paraprotein and infectious studies from the phenotype with correct collection timing.
3Arrange neurology, haematology or rheumatology review and imaging when systemic signs are present; do not prescribe empirical lifelong anticoagulation from skin appearance alone.

04Livedoid ulcer routeConfirm thrombotic disease and close painful woundsRecurrent ankle or foot pain progresses to small ulcers and atrophie-blanche scars.

1Assess pulses, venous disease, neuropathy, infection and pain and obtain a deep active-edge biopsy when diagnosis remains uncertain or treatment risk is substantial.
2Use non-adherent wound care, smoking cessation, safe analgesia and compression only after arterial assessment and control any identified autoimmune, haematological or thrombotic driver.
3Discuss antiplatelet, anticoagulant or other specialist therapy through dermatology and haematology, defining bleeding safeguards and a measurable ulcer and pain response.

05Cholesterol embolic routeRecognise the pulse-preserved blue toeLivedo or blue digits and renal decline follow angiography, vascular surgery or a change in anticoagulation.

1Admit or urgently assess organ severity, examine all pulses and skin and request FBC with eosinophils, renal and urine tests, inflammatory markers and vascular imaging.
2Coordinate vascular, renal and cardiology evaluation of the embolic source and avoid further invasive arterial procedures unless the expected benefit justifies additional showering risk.
3Use tissue biopsy only when it will change management and the site can heal, targeting viable skin rather than an end-stage necrotic toe.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Skin infarction and infection

Fixed occlusion progresses to necrosis, ulcer, secondary infection, osteomyelitis, scarring and occasionally digit or limb loss.

Cerebral ischaemia

APS, Sneddon syndrome and embolic disease can cause transient deficits, stroke, cognitive decline and recurrent neurological disability.

Renal and visceral emboli

Cholesterol, thrombotic and inflammatory disease can injure kidneys and bowel, producing renal failure, hypertension, abdominal pain, bleeding or infarction.

Pregnancy morbidity

Placental thrombosis and related mechanisms in APS cause recurrent loss, fetal growth restriction, pre-eclampsia and premature birth.

Antithrombotic harm

Empirical or poorly monitored antiplatelet and anticoagulant therapy can cause major bleeding, interactions and procedural risk without treating a non-thrombotic mechanism.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

For physiological livedo, confirm complete warming response and provide return advice for persistence, pain, ulcer, asymmetry or neurological symptoms.
For livedo racemosa, document network extent and new cerebral, renal, pregnancy or thrombotic events and ensure repeat APS testing occurs no sooner than twelve weeks when indicated.
For retiform disease, measure pain, temperature, pulses, viable margin and necrosis frequently and escalate any spreading tissue loss or infection.
For livedoid ulcers, record new-lesion count, pain, ulcer area, healing and atrophie blanche and monitor compression tolerance and wound infection.
During any antiplatelet or anticoagulant treatment, verify indication, agent, dose, renal function, interactions, adherence and bleeding and thrombosis symptoms at each review.
After cholesterol embolisation, follow kidney, skin, gastrointestinal and neurological trajectory and optimise vascular risk without assuming palpable pulses mean recovery.
Reassess the diagnosis when a livedoid pattern becomes nodular, palpable, ulcerated or systemically inflammatory, because mechanism may have changed or been mixed.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

A net is haemodynamics

Slow deoxygenated blood becomes visible around paler central cones, so temperature and flow can produce a striking pattern without fixed vessel damage.

Broken meshes carry weight

Irregular open arcs over trunk or buttocks are more concerning than a fine symmetrical cold-induced lattice and deserve systemic history and examination.

Retiform means tissue at risk

Once a network is fixed, angular and non-blanching, the question shifts from cosmetic vasospasm to which vessel has occluded or been destroyed.

Pulses survive microemboli

Cholesterol crystals obstruct arterioles downstream of palpable arteries, explaining blue toes and renal injury despite preserved proximal pulses.

APS needs persistence

Acute infection and medicines can create transient or uninterpretable antibodies, so a compatible clinical event and repeat positivity prevent overdiagnosis.

Atrophie blanche is an endpoint

Porcelain-white stellate scarring can follow livedoid vasculopathy but also severe venous or inflammatory ulceration and is not diagnostic without the history.

11Common pitfallsFrequent interpretation and management errors.

01
Reassuring persistent broken livedo because the room is cold without documenting a warming response.
02
Calling fixed retiform necrosis livedo reticularis and missing acute arterial occlusion, calciphylaxis or DIC.
03
Assuming palpable pulses exclude cholesterol emboli or other small-vessel ischaemia.
04
Diagnosing APS from one low or transient antibody result without a qualifying clinical event and repeat testing.
05
Sending cryoglobulin blood through an ordinary cold pathway and accepting a false-negative result.
06
Biopsying only black infarcted centre or too superficially to include the causal vessels.
07
Starting lifelong anticoagulation for skin colour without defining mechanism, bleeding risk and specialist ownership.