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- Polyarteritis nodosa (PAN) is an antineutrophil cytoplasmic antibody (ANCA)-negative necrotizing arteritis of medium or small arteries without glomerulonephritis or vasculitis of arterioles, capillaries, or venules (1).
- Involved systems include GI tract, peripheral nervous system (sensory and motor), central nervous system (CNS), renal (without glomerulonephritis), skin, testes/epididymis, heart (1,2)
- Features depend on location of vasculitis: mesenteric ischemia–related symptoms, new onset or worsening hypertension (HTN), mononeuritis multiplex, purpuric or nodular skin lesions, or livedo reticularis (2).
- Renal disease in PAN usually manifests as HTN and mild proteinuria with/without azotemia. Renal infarction may occur (2).
- PAN formerly encompassed several distinct entities (classic PAN, microscopic PAN, cutaneous PAN). With ANCA testing, microscopic PAN appears pathophysiologically unrelated to the other two.
- Classic PAN is ANCA-negative (1,3).
- Microscopic PAN has ANCAs directed against myeloperoxidase (MPO) and involvement of small arterioles (microscopic polyangiitis [MPA]). This is now classified as ANCA-associated vasculitis (1).
- Cutaneous (or limited) PAN is a chronic disease with cutaneous lesions with characteristic histopathologic features of PAN. There are few systemic manifestations, although myalgias and peripheral motor neuropathy (mononeuritis multiplex) or sensory neuropathy may be present. ANCA positivity is variable (2,4).
- Synonym(s): periarteritis; panarteritis; necrotizing arteritis
- Predominant age: Peaks in 5th to 6th decade; incidence rises with age.
- 1.5:1 male predominance
Rare: 2 to 33 cases/1 million adults (4)
Etiology and Pathophysiology
- Segmental, transmural, necrotizing inflammation of medium and small muscular arteries, with intimal proliferation, thrombosis, and ischemia of the organ/tissue supplied by the affected arteries; aneurysm formation at vessel bifurcations (2)
- Hepatitis B–related PAN results in direct injury to the vessel due to viral replication or deposition of immune complexes, with complement activation and subsequent inflammatory response (2).
- Most cases are idiopathic; 20% are related to hepatitis B or C infection.
- In patients with PAN and hepatitis B, HBsAg has been recovered from involved vessel walls.
Mutations of adenosine deaminase 2 (ADA 2) have been identified in families with PAN (5).
Hepatitis B infection > hepatitis C infection (cutaneous PAN)
Commonly Associated Conditions
- Hepatitis B (strong association with classic PAN)
- Hepatitis C (less strongly linked to cutaneous PAN)
- Hairy cell leukemia
- 27 cases of systemic PAN following Hepatitis B vaccination
- Minocycline (symptoms resolve on stopping drug, reoccur if rechallenged)
- Case-based associations with CMV infection, amphetamines, and interferon