Polyarteritis nodosa is a systemic vasculitis characterized by necrotizing inflammatory lesions that affect medium and small muscular arteries, preferentially at vessel bifurcations, resulting in microaneurysm formation, aneurysmal rupture with hemorrhage, thrombosis, and, consequently, organ ischemia or infarction.  Nonspecific, firm, tender subcutaneous nodules without livedo reticularis and/or systemic involvement may be the first sign of polyarteritis [...]