Rheumatology

	Answer 5 Peripheral nerve biopsy. Based on this patient’s hypertension, skin lesions, and neurologic disturbances, sural nerve biopsy is most appropriate to confirm the diagnosis of PAN.4 In PAN, the biopsy will show a necrotizing pattern of vasculitis in medium-sized vessels in the epineurium as well as vessels in various stages of the disease process, such as with fibrinoid necrosis with acute inflammation and scarring and organizing thrombi. A muscle biopsy has a sensitivity of 50% in diagnosing PAN.5 Renal biopsy has a lower specificity for diagnosing PAN and is associated with an increased risk of bleeding as a result of microaneurysms in the kidney.6 Angiographic studies should only be performed if there is no dermatologic or renal involvement and are not the best option in this patient given his elevated serum creatinine level. REFERENCES 4. Ohkoshi N, Migusama H, Oguni E, Shoji S. Sural nerve biopsy in vasculitic neuropathies: morphometric analysis of the caliber of involved vessels. J Med 1996;27:153-70. 5. Dahlberg PJ, Lockhart JM, Overhalt EL. Diagnostic studies for systemic necrotizing vasculitis: sensitivity, specificity, and predictive value in patients with multisystem disease. Arch Intern Med 1989;149:161-5. 6. Guillevin L. Polyarteritis nodosa and microscopic polyangiitis. In: Ball GV, Bridges SL Jr, editors. Vasculitis. New York: Oxford University Press; 2002:300-20. Click here to return to the questions
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