Livedo reticularis from amantadine.

A 70-year-old Caucasian man with a medical history of Parkinson's disease presented with a 3-month history of violaceous reticulated patches on his upper and lower extremities. The lesions were asymptomatic. The patient did not have a history of cardioembolic events or autoimmune disorders. No new medications were started before the onset of the lesions. Review of systems was unremarkable. On examination, large erythematous to violaceous patches were present in a reticulated net-like pattern on the patient's upper and lower extremities (Figure 1 and Figure 2). No edema, erosions, or ulcerations were noted. An extensive workup for autoimmune, infectious, and hematologic causes of livedo reticularis was performed. Complete blood cell count, anti-nuclear antibodies (ANAs), anti-Ro and anti-La antibodies, antiphospholipid antibodies, protein C and S levels, cryoglobulin screen, rheumatoid factor, and hepatitis screen were all within normal limits. After these potential other causes were excluded, the patient was diagnosed with amantadine-induced livedo reticularis (LR), a medication he had been taking for 2 years for Parkinson's disease. The patient's dose of amantadine was decreased from 100 mg to 50 mg twice daily and over the next few months, his lesions gradually faded. Because his neurologic condition benefited from amantadine and his lesions were asymptomatic, his neurologist continued the medication.