A 50-year-old drug abuser presents with fever and weight loss. Exam shows hypeension, nodular skin rash, and peripheral neuropathy. ESR is 100 mm/L, and RBC casts are seen on urinalysis. The most likely condition is:

The 50-year-old gentleman is a drug abuser and also has a multisystem disease, including systemic complaints, hypeension, skin lesions, neuropathy, and an abnormal urine sediment. This complex suggests a vasculitis, paicularly polyaeritis nodosa. 20 to 30% of patients have hepatitis B antigenemia. The disease is a necrotizing vasculitis of small and medium muscular aeries. The pathology of the kidney includes an aeritis and, in some cases, a glomerulitis. Nodular skin lesions show vasculitis on biopsy.