Levamisole-Induced Leukocytoclastic Vasculitis with Negative Serology in a Cocaine User

BACKGROUND Levamisole is a common adulterant of cocaine. It can cause agranulocytosis and cutaneous vasculitis that can possibly lead to cutaneous necrosis. In all reported cases of levamisole-induced vasculitis, it has been described as a clinical syndrome characterized by a constellation of typical clinical features and a positive serum serology for ANCA levels, especially very high-titer p-ANCA levels, in the background of cocaine abuse. However, patients may have a negative serology and here, we present the first such case. CASE REPORT A 58-year-old African American man with a history of polysubstance abuse, 4 days after last cocaine use, presented with sudden onset of painful pruritic rash and polyarthralgias. He was found to have normal vital signs, with bilateral tender knees and erythematous-purplish maculopapular lesions involving the abdomen and the left thigh. Laboratory work-up was significant for elevated CRP, negative c-ANCA, p-ANCA ANA, and RA levels, and a positive urine toxicology for cocaine. Urine analysis by high-performance liquid chromatography was positive for levamisole. Ultimately, a final diagnosis was made by skin biopsy, which revealed findings suggestive of leukocytoclastic vasculitis. CONCLUSIONS Cutaneous leukocytoclastic vasculitis can be caused by levamisole, which is used as an adulterant in cocaine. Most cases are associated with positive ANCA levels; however, a negative serology is also a possibility.