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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
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.
Relatively rare in males. When present in the male gender, a secondary cause should be suspected.
Often coexists with RP and/or acrocyanosis.
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ETIOLOGY AND PATHOPHYSIOLOGY
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LR is most commonly a primary disorder. Less often, a variety of secondary causes can provoke LR (Table 75-1).
Livedo racemosa is always due to a secondary disorder (Table 75-1).
A variety of medications have been associated with LR (Table 75-2).
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
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.
Venodilatation of the venous plexus may be caused by hypoxia or autonomic dysfunction.
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