<prompt> A 50-year-old drug abuser presents with fever and weight loss. Exam shows hypeension, nodular skin rash, and peripheral neuropathy. ESR is 100 mmL, and RBC casts are seen on urinalysis. The most likely condition is:Reiter syndromeDrug-induced lupus erythematosusPolyaeritis nodosaBehcet syndrome  <response>: 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. 