Polyarteritis Nodosa Diagnosis and Treatment

Diagnostic Approach

• For a patient with suspected polyarteritis nodosa (PAN), particularly with systemic symptoms, obtain tissue biopsy from the most accessible symptomatic site and abdominal vascular imaging to confirm diagnosis before initiating treatment, as recommended by the American College of Rheumatology 1, 2
• Tissue confirmation is preferred over imaging alone, according to the American College of Rheumatology 1, 2
• Histologic findings should include mixed-cell inflammatory infiltrates, fibrinoid necrosis, and absence of granulomas, as stated by the American College of Rheumatology 1, 2

Treatment Strategy

• For idiopathic severe PAN, initiate treatment with cyclophosphamide and high-dose glucocorticoids immediately, as recommended by the American College of Rheumatology 1, 2, 3
• Glucocorticoid administration should use intravenous pulse glucocorticoids over high-dose oral glucocorticoids for severe disease, according to the American College of Rheumatology 3
• Cyclophosphamide is strongly preferred over rituximab for newly diagnosed severe PAN, as stated by the American College of Rheumatology 3
• Do not add plasmapheresis to cyclophosphamide and glucocorticoids in idiopathic PAN, as there is no added benefit, according to the American College of Rheumatology 3
• For non-severe disease, treatment with non-cyclophosphamide immunosuppressive agents (methotrexate or azathioprine) plus glucocorticoids is recommended, as stated by the American College of Rheumatology 3

Maintenance and Long-term Management

• After achieving remission, transition from cyclophosphamide to a less toxic agent (methotrexate or azathioprine) once remission is achieved, as recommended by the American College of Rheumatology 3
• Continue non-glucocorticoid immunosuppressive therapy for 18 months total, according to the American College of Rheumatology 3
• Taper glucocorticoids based on clinical response, with optimal duration not well-established but guided by disease activity, as stated by the American College of Rheumatology 3
• Discontinue immunosuppression after 18 months if sustained remission, as recommended by the American College of Rheumatology 3
• Repeat vascular imaging if new symptoms suggest relapse, according to the American College of Rheumatology 3

Polyarteritis Nodosa Diagnosis and Treatment

Clinical Manifestations

• Fever and weight loss are common presenting symptoms in patients with Polyarteritis Nodosa (PAN), according to the American College of Rheumatology 4, 5
• Skin nodules and livedo reticularis are common cutaneous manifestations in PAN patients, as reported by the American College of Rheumatology 4, 5
• Abdominal pain is frequently reported in PAN patients, as noted by the American College of Rheumatology 4, 5
• Renal insufficiency may occur due to vascular involvement in PAN, as reported by the American College of Rheumatology 5, 6
• Mesenteric ischemia can occur due to involvement of mesenteric vessels in PAN, according to the American College of Rheumatology 7

Diagnostic Approach

• Abdominal vascular imaging is recommended to aid in establishing diagnosis and determining disease extent in PAN, as suggested by the American College of Rheumatology 8
• Angiography may reveal saccular or fusiform aneurysms and stenotic lesions in mesenteric, hepatic, and renal arteries in PAN patients, according to the American College of Rheumatology 5
• Deep skin biopsy is preferred over superficial skin punch biopsy when skin involvement is suspected in PAN, as recommended by the American College of Rheumatology 8

Treatment Recommendations

• For newly diagnosed active, severe PAN, treatment with cyclophosphamide and high-dose glucocorticoids is recommended over glucocorticoids alone, according to the American College of Rheumatology 6, 9
• Intravenous pulse glucocorticoids are preferred over high-dose oral glucocorticoids for initial treatment of severe PAN, as suggested by the American College of Rheumatology 8, 9
• After achieving remission with cyclophosphamide, transition to another less toxic immunosuppressive agent such as methotrexate or azathioprine is recommended, according to the American College of Rheumatology 6, 9

Prognosis and Monitoring

• Untreated severe PAN has a mortality rate of approximately 40% at 5 years, as reported by the American College of Rheumatology 5
• Serial neurologic examinations are preferred over repeated electromyography/nerve conduction studies for monitoring disease activity in patients with peripheral motor neuropathy, according to the American College of Rheumatology 8

Guideline Recommendations for the Diagnosis of Classical Polyarteritis Nodosa

Clinical Presentation

• Peripheral neuropathy (mononeuritis multiplex or sensory/motor deficits) is a key manifestation that should raise suspicion for polyarteritis nodosa. 10

Tissue Biopsy Recommendations

• Deep skin biopsy that reaches the medium‑sized vessels of the dermis is preferred over superficial punch biopsy for patients with cutaneous involvement, because it is more likely to capture the characteristic necrotizing vasculitis. 10
• Combined nerve‑and‑muscle biopsy provides a higher diagnostic yield than nerve biopsy alone when evaluating peripheral neuropathy in suspected PAN. 10
• When performing nerve biopsy, sample a purely sensory nerve (e.g., the sural nerve) to avoid iatrogenic motor deficits. 11

Vascular Imaging

• Conventional angiography is the current gold‑standard imaging modality for abdominal vascular assessment in PAN, offering superior resolution. 10
• CT angiography or MR angiography are acceptable non‑invasive alternatives when conventional angiography is not feasible. 10

Follow‑up Imaging

• In patients with severe PAN and abdominal involvement who achieve clinical remission, conditional follow‑up abdominal vascular imaging is recommended, especially if the initial study demonstrated aneurysmal disease. 10
• Indefinite routine imaging is not advised when vascular disease is quiescent. 11

Neurologic Monitoring

• For PAN‑related peripheral motor neuropathy, serial neurologic examinations are preferred over routine repeat electromyography/nerve‑conduction studies every six months, as repeated EMG is invasive and unnecessary in stable patients. 11
• Repeat EMG should be performed only if new or worsening neurologic symptoms develop. 11

Biopsy Pitfalls to Avoid

• Superficial skin biopsies frequently miss the medium‑sized vessels involved in PAN and should therefore be avoided. 10
• Blind biopsies of tissue that is not clinically affected are discouraged, as they reduce diagnostic yield. 11

Evidence‑Based Management of Polyarteritis Nodosa

Induction and Maintenance Therapy for Severe Idiopathic PAN

• Initiate combination therapy with cyclophosphamide and high‑dose glucocorticoids immediately in newly diagnosed severe idiopathic PAN that presents with organ‑threatening manifestations (e.g., renal insufficiency, tissue ischemia, mesenteric involvement). Strong recommendation. 12
• After achieving remission, switch from cyclophosphamide to a non‑cyclophosphamide immunosuppressant (methotrexate or azathioprine) to limit cumulative toxicity. Strong recommendation. 12

Treatment of Limited/Non‑Severe PAN

• Manage non‑severe PAN with methotrexate or azathioprine together with glucocorticoids, reserving cyclophosphamide for severe disease. Conditional recommendation. 12

Hepatitis B‑Associated PAN (HBV‑PAN)

• Prioritize antiviral therapy (e.g., nucleos(t)ide analogues) combined with plasmapheresis; use only short‑term corticosteroids and avoid prolonged cyclophosphamide. Strong recommendation. 12

Deficiency of Adenosine Deaminase 2 (DADA2)–Related PAN‑Like Vasculitis

• Consider DADA2 in early‑onset PAN‑like disease with recurrent strokes; confirm diagnosis with ADA2 gene sequencing or functional assays. Strong recommendation. 12
• Treat confirmed DADA2 with tumor‑necrosis‑factor (TNF) inhibitors rather than glucocorticoids alone, as TNF blockade more effectively prevents strokes. Strong recommendation. 12

Adjunctive Therapies

• Offer physical therapy to patients with nerve and/or muscle involvement, especially those with marked motor deficits; the intervention carries minimal risk and potential functional benefit. Conditional recommendation. 12

Cardiac Involvement in PAN

• Perform coronary angiography to differentiate vasculitic coronary disease from atherosclerosis in PAN patients with cardiac manifestations. Strong recommendation. 13
• Recognize that cardiac involvement occurs in approximately 5–20 % of PAN cases and is more frequent in HBV‑associated disease. Observational data. 13
• Acknowledge that PAN can cause myocardial dysfunction through coronary angiitis, myocardial infarction, and hypertension; aggressive blood‑pressure control is essential in autoimmune‑mediated heart failure. Strong recommendation. 13
• Understand that development of heart failure signals a poor prognosis. Observational data. 13
• Treat cardiac PAN with high‑dose steroids plus selective coronary revascularization, and address concurrent active HBV infection when present. Strong recommendation. 13