Levamisole is an immunomodulatory drug that had been used to treat various medical conditions, including parasitic infections, nephrotic syndrome, and colorectal cancer,1 before being withdrawn from the US market in 2000. The most common reasons for levamisole discontinuation were leukopenia and rashes (1%–2%),1 many of which included leg ulcers and necrotizing purpura of the ears.1,2 The drug is currently available only as a deworming agent in veterinary medicine.
Since 2007, increasing amounts of levamisole have been used as an adulterant in cocaine. In 2007, less than 10% of cocaine was contaminated with levamisole, with an increase to 77% by 2010.3 In addition, 78% of 249 urine toxicology screens that were positive for cocaine in an inner city hospital also tested positive for levamisole.4 Levamisole-cut cocaine has become a concern because it is associated with a life-threatening syndrome involving a necrotizing purpuric rash, autoantibody production, and leukopenia.5
Levamisole-induced vasculitis is an independent entity from cocaine-induced vasculitis, which is associated with skin findings ranging from palpable purpura and chronic ulcers to digital infarction secondary to its vasospastic activity.6-8 Cocaine-induced vasculopathy has been related to cytoplasmic antineutrophil cytoplasmic antibody positivity and often resembles Wegener granulomatosis.6 Although both cocaine and levamisole have reportedly caused acrally distributed purpura and vasculopathy, levamisole is specifically associated with retiform purpura, ear involvement, and leukopenia.6,9 In addition, levamisole-induced skin reactions have been linked to specific antibodies, including antinuclear, antiphospholipid, and perinuclear antineutrophil cytoplasmic antibody (p-ANCA).2,5-7,9-14
We present a case of refractory levamisole-induced vasculitis and review its clinical presentation, diagnostic approach, laboratory findings, histology, and management. Furthermore, we discuss the possibility of a new treatment option for levamisole-induced vasculitis for patients with refractory disease or for patients who continue to use levamisole.