A 32-year-old healthy woman with subjective cold sensitivity presents with a “fishnet” appearing rash on her thighs and calves. It has been present for at least 10 years and is symmetrical, nonpainful, and has never ulcerated (Figure 75-1). The discoloration is most pronounced when she is cold and nearly dissipates in a warm environment. Her fingers manifest the well-demarcated cold-associated pallor of Raynaud phenomenon (RP). The appearance is consistent with livedo reticularis (LR).

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  Livedo reticularis is a common but often unrecognized vasospastic disease.¹

  
  
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  LR typically affects young to middle-aged women (20-50 years of age) who are otherwise healthy. Up to 50% of young females may be affected in cold environments.

  
  
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  Relatively rare in males. When present in the male gender, a secondary cause should be suspected.

  
  
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  Often coexists with RP and/or acrocyanosis.

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  LR is most commonly a primary disorder. Less often, a variety of secondary causes can provoke LR (Table 75-1).

  
  
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  Livedo racemosa is always due to a secondary disorder (Table 75-1).

  
  
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  A variety of medications have been associated with LR (Table 75-2).

  
  
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  LR results from physiologic or sometimes pathophysiologic changes with the cutaneous microvascular system. Livedo racemosa is always due to a pathophysiologic small vessel process.²

  
  
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  Livedo arises from either deoxygenation or venodilatation within the conical-appearing subpapillary venous plexus. Decreased arteriolar perfusion is the predominant cause of deoxygenation within the venous plexus. Impaired arterial perfusion usually results from vasospasm, although hyperviscosity, inflammation, and/or thromboemboli can be causative as well. One or a combination of the latter three mechanisms underlies the pathophysiologic cutaneous changes of secondary LR or livedo racemosa. Increased resistance to venous outflow is a less frequent cause of deoxygenation.

  
  
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  Venodilatation of the venous plexus may be caused by hypoxia or autonomic dysfunction.

Clinical Features

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  LR—fishnet or ring-like uniform violaceous mottling of the skin. The rings are regular and complete (Figure 75-2).

  
  
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  Livedo racemosa—irregular violaceous mottling with broken rings (Figure 75-3).

  
  
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  In both LR and livedo racemosa, the skin is palpably cool.

  
  
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  The discoloration of livedo is provoked or exacerbated by cold exposure. Resolution or improvement occurs when exposed to heat. Primary LR is completely reversible. If the livedoid mottling fails to completely resolve in a warm environment, a secondary cause of LR should be suspected. Livedo racemosa is fixed and will not completely resolve in a warm setting.

  
  
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  Leg dependency aggravates the discoloration, whereas elevation improves it.

  
  
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  Usually asymptomatic, although cold-associated tingling or numbness rarely occurs.

  
  
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  If concurrent purpura, nodules, macules, ulcerations, and/or atrophie blanche are noted, a secondary cause of LR or livedo racemosa exists (Figure 75-4).

  
  
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  Patients with livedo racemosa have a significantly higher frequency of skin ulcerations, arthralgias, cutaneous vasculitis, and higher c-reactive protein (crp) levels when compared to their lr counterparts.³

  
  
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  With exception of the characteristic skin changes, the examination in primary LR is usually unremarkable with the exception of possible associated RP or acrocyanosis. Patients with secondary LR or livedo racemosa may display manifestations related to the associated disease (eg, hemiparesis in Sneddon syndrome, Gottron papules in dermatomyositis, lower extremity purpura, and ulcerations in livedoid vasculopathy).

  
  
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  Livedo racemosa is a marker for arteriovenous thrombosis even in the absence of antiphospholipid antibodies.⁴