Snapshot A 52-year-old man presents to the emergency department with abdominal pain and rectal bleeding. His symptoms are associated with malaise, fever, and weight loss. He does not have a family history of malignancy and his last colonoscopy was unremarkable. His blood pressure is 155/98 mmHg (his blood pressure is usually 125/74 mmHg). On physical exam, he has abdominal tenderness, livedo reticularis, and cutaneous ulcers. Laboratory testing is notable for a newly elevated creatinine of 2.6 mg/dL, erythrocyte sedimentation rate, and C-reactive protein. He is also seropositive for hepatitis B virus, ANCA-negative, and guaiac positive. Introduction Clinical definition medium vessel systemic necrotizing vasculitis not associated with ANCA antibodies Epidemiology Demographics 50-70 years of age Risk factors hepatitis B virus Etiology Idiopathic (most common) Secondary polyarteritis nodosa can result from hepatitis B infection hepatitis C infection hairy cell leukemia Pathogenesis type III hypersensitivity reaction leading to artery occlusion or rupture which can result in organ ischemia and hemorrhage Presentation Symptoms/physical exam systemic symptoms fever weight loss malaise neurologic mononeuritis multiplex polyneuropathy stroke confusion musculoskeletal articular pain extremity pain skin ulcers livedo reticularis purpura renal glomerulonephritis hematuria new onset hypertension pulmonary typically spares lungs, though may involve bronchial arteries gastrointestinal abdominal pain rectal bleeding Imaging Angiography indication considered in patients suspected of having polyarteritis nodosa in the setting of being unable to obtain a histologic diagnosis findings arterial microaneurysms (saccular or fusiform) with stenotic lesions typically affecting arterial branches of the kidney mesentery liver Studies Studies ↑ erythrocyte sedimentation rate ↑ C-reactive protein may be positive for hepatitis B virus (~30% of patients) hepatitis C virus parvovirus B19 virus HIV Biopsy confirms the diagnosis must biopsy the clinically affected organ demonstrates medium vessel vasculitis Differential Granulomatosis with polyangiitis differentiating factors ANCA-positive vasculitis affects the upper and lower respiratory tracts and kidneys affects small vessels Microscopic polyangiitis differentiating factors ANCA-positive vasculitis similar to granulomatosis with polyangiitis without nasopharyngeal involvement affects small vessels Treatment Medical high-dose corticosteroids with cyclophosphamide indication in patients with moderate to severe disease Complications Thrombosis Hemorrhage Ulcers Prognosis In untreated cases, it is associated with a poor prognosis Hepatitis B-associated disease has a worse prognosis