Polyarteritis nodosa (PAN) is a systemic vasculitis of medium-sized vessels that most commonly affects the skin, peripheral nerves, muscles, joints, gastrointestinal tract, and kidneys, but usually spares the lungs. Most cases are idiopathic, but PAN is associated with certain viral infections, most commonly hepatitis B virus (HBV) infection. Patients typically present with constitutional symptoms (e.g., fever, weight loss, muscle and joint pain); additional symptoms vary based on the organ of involvement (e.g., acute kidney injury, myocardial infarction, rash). ANCAs and cryoglobulins are typically negative on laboratory studies. The diagnosis is confirmed via biopsy or visceral angiography of the affected organs. Management typically involves immunosuppressive agents (e.g., glucocorticoids). For patients with HBV-associated PAN, antiviral therapy and, in selected cases, plasmapheresis, are also indicated.
- Nonspecific symptoms
- Renal involvement (∼ 60%): hypertension, renal impairment 
- Coronary artery involvement (∼ 35%); ↑ risk of myocardial infarction
- Skin involvement (∼ 40%): rash, ulcerations, nodules
- Neurological involvement: polyneuropathy (mononeuritis multiplex), stroke
- GI involvement: abdominal pain, melena, nausea, vomiting
- Usually spares the lungs
In PAN, the Pulmonary Artery is Not involved, PANmural inflammation of the arterial wall is present, and PAN may be associated with hePAtitis B.
General principles 
- PAN may involve various organs; no symptom is pathognomonic for PAN.
- The absence of lung involvement and glomerulonephritis helps differentiate PAN from other systemic necrotizing vasculitides (e.g., ANCA-associated vasculitis).
- Laboratory studies further support the diagnosis and help determine the underlying etiology.
- A biopsy or visceral angiography is required to confirm the diagnosis.
Laboratory studies 
- Inflammatory markers
- Additional studies
Imaging studies 
- Visceral angiography of affected organs
- CTA or MRA
Biopsy of affected tissue 
- Indications: patients with accessible affected tissue (e.g., muscle; , skin, sural nerve) 
Most guideline recommendations are based on low-level evidence or expert opinion. Use shared decision-making. 
- Consult rheumatology and/or other specialties as required.
- Immunosuppressants (e.g., glucocorticoids; PLUS cyclophosphamide) are indicated for all patients to achieve remission.
- Antiviral therapy; is indicated for HBV-associated PAN.
- Patients with nerve and/or muscle involvement often benefit from physical therapy.
- Initial therapy: Start remission induction therapy for patients with active disease.
- Maintenance of remission: glucocorticoids PLUS a glucocorticoid-sparing agent (e.g., methotrexate or azathioprine) 
- Sustained remission: Therapy may be discontinued.
Some patients achieve remission with glucocorticoid monotherapy, however, the addition of glucocorticoid-sparing agents reduces the dose of glucocorticoids required, reducing the potential adverse effects. 
HBV-associated PAN 
- Consult a hepatologist for all patients; see “Treatment” in “Hepatitis B.”
- All patients require a 2-week course of high-dose glucocorticoids before antiviral therapy.
- Plasmapheresis may be considered.
- Monitor for .
- Consider .