Mimics of Vasculitis

Ernest Maningding; Tanaz A. Kermani

Disclosures

Rheumatology. 2021;60(1):34-47. 

In This Article

Thrombotic and Hypercoagulable Conditions

Thrombotic and coagulopathic disorders mimic medium and small vessel vasculitis through shared skin manifestations like purpura, livedo reticularis and ulcerations.[89] Retiform purpurae should raise concern for thrombotic and hypercoagulable disorders.[90] The distinction between thrombosis and vasculitis can be particularly challenging when multiple vascular beds are affected, leading to multi-organ involvement, as in the case of disseminated intravascular coagulation, thrombotic thrombocytopenic purpura and APS.[91,92] In most cases, clinical presentation, laboratory studies and biopsy can distinguish between vasculitis and these mimics.

Thrombotic Microangiopathy (TMA)

TMAs include hereditary or acquired conditions and are characterized by microangiopathic haemolytic anaemia, thrombocytopenia and organ injury.[92] TMA can be in association with autoimmune diseases, including SLE, systemic sclerosis and aPL syndrome, among others.[92] Renal involvement is typical of primary TMA syndromes, and CNS manifestations like headache, confusion, tonic-clonic seizures, stroke or coma can also occur.[92] Cutaneous manifestations include purpura.[92] Regardless of the aetiology, TMA histopathology shows vascular damage with swelling of the endothelial and subendothelial space and vessel wall thickening and platelet microthrombi in small arterioles and capillaries causing luminal occlusion, which should help distinguish it from vasculitis.[92]

Acquired Hypercoagulability From Anticoagulation

Warfarin-induced skin necrosis and heparin-induced thrombocytopenia can cause cutaneous manifestations including skin necrosis.[89] Warfarin-induced skin necrosis typically occurs within 3–5 days of initiation of therapy and affects areas of the body with high fat content, like the breasts, buttocks, abdomen, thighs and calves.[89] Heparin-induced thrombocytopenia is a potentially life-threatening complication of heparin exposure resulting from a complex of autoantibodies against endogenous platelet factor 4 and heparin causing activation of platelets and monocytes.[93] The onset is typically between 5 and 10 days after exposure to heparin.[93] Clinical manifestations include venous thromboembolism, but skin necrosis and arterial thrombosis, including peripheral arterial thrombosis, stroke and rarely myocardial infarction, can also occur.[93] Diagnosis is made based on clinical findings, a decrease in platelet count and antibody testing.[93] Clinical history, including exposure to the above anticoagulants and timing of onset of manifestations, can help distinguish these entities from vasculitis.

APS

The diagnosis of APS is supported by the 2006 revised Sapporo classification criteria, which requires the presence of at least one clinical criteria—vascular thrombosis or particular adverse pregnancy outcomes—and the persistent presence of at least one aPL (i.e. aCL, anti-β2-glycoprotein I or lupus anticoagulant).[91] Common clinical features include deep vein thrombosis (32%), thrombocytopenia (<100 000 platelets/μl) (22%), livedo reticularis (20%) and stroke (13.1%).[91]

Livedoid Vasculopathy

Livedoid vasculopathy is a chronic, non-inflammatory, thrombo-occlusive, cutaneous vasculopathy affecting the lower extremities and feet.[94] It can be primary (idiopathic) or secondary (associated with coagulation disorders).[94] Clinical findings include livedoid changes, atrophie blanche (smooth, ivory-white plaques) and recurrent, painful skin ulcerations.[94] Histopathology in livedoid vasculopathy demonstrates intraluminal thrombi and prominent hyalinization of vessel walls with scant perivascular inflammation.[89,94] Direct immunofluorescence is positive for fibrin, complement and immunoglobulin deposition in dermal vessels.[89,94] True vasculitis is usually absent.[94]

Summary

Evaluation of cutaneous manifestations like purpura and livedo require consideration of thrombotic and hypercoagulable disorders. Thrombotic conditions like thrombotic thrombocytopenic purpura and APS can affect multiple vascular beds and cause renal manifestations or multi-organ failure. Diagnosis requires consideration of these conditions, laboratory studies and, in some cases, biopsy to distinguish between vasculitis and these mimics.

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