Livedo reticularis

Livedo reticularis is a mottled, recticulated red-purple discoloration of the skin. 

Causes include:

• Idiopathic 
• Secondary 
• Occlusive disease 
• Emboli 
• Thrombocytosis 
• Cold agglutinins 
• Cryoglobulins 
• Rheumatic
• PAN 
• SLE 
• RA 
• Infections 
• TB 
• Syphilis 
• Pseudomonas 
• Other 
• Pancreatitis 
• Lymphoma 
• Hypercalcaemia 

Note the similarity in appearance between livedo reticularis and erythema ab igne. 

References:

Adams, S. Dermacase. Livedo reticularis secondary to lupus erythematosus. Cam Fam Physician. 1999; 45(51):64. 

Livedo reticularis. Dermnet NZ. Available at http://dermnetnz.org/vascular/livedo-vascularis.html