Polyarteritis Nodosa (PAN) (Polyarteritis; Periarteritis Nodosa) By Alexandra Villa-Forte, MD, MPH, Cleveland Clinic Reviewed / Revised Jun 2022 | Modified Sep 2022 View Patient Education Etiology Pathophysiology Symptoms and Signs Diagnosis Prognosis Treatment Key Points Polyarteritis nodosa is a systemic necrotizing vasculitis that typically affects medium-sized muscular arteries and occasionally affects small muscular arteries, resulting in secondary tissue ischemia.