Polyarteritis nodosa

Background

• Necrotizing vasculitis of small- and medium-sized blood vessels
• Skin, musculoskeletal, CNS, and GI tract (spares lung)
• Predilection to arterial bifurcations and branch sites
• Microaneurysm, thrombosis, emboli, organic ischemia, and infarction
• Etiology: Idiopathic, HBV, HCV, hairy cell leukemia

Diagnosis

Clinical Features

• Cutaneous lesion + adult onset HTN
• Men > women (2:1)
• Peak age 40-60s
• Systemic: Fatigue, weight loss, weakness, fever, arthralgia
• Cutaneous lesions (1/3 patients)
  • Tender erythematous nodules
  • Palpable pupura (fingers, ankles, malleoli, pretibial)
  • Digital cyanosis
  • Splinter hemorrhages
  • Livedo reticularis
• Renovascular arteritis → HTN
• Peripheral neuropathies (mononeuritis multiplex, polyneuropathy)
• Mesenteric vasculitis (abdominal angina, ischemia, infarction, perforation)
• Myocardial ischemia and heart failure
• Myalgia (elevated CK)

Classification

• American College of Rheumatology 10 criteria (at least 3, has 82% sensitivity and 87% specificity)
  • Unexplained weight loss greater than 4kg
  • Livedo reticularis
  • Testicular pain or tenderness
  • Myalgia (excluding shoulder and hip girdle), weakness of muscles, tenderness of leg muscles, or polyneuropathy
  • Mononeuropathy or polyneuropathy
  • New-onset diastolic blood pressure > 90mmHg
  • Elevated serum BUN (>40mg/dL or 14.3mmol/L) or Cr (>1.5mg/dL or 132 mmol/L)
  • Evidence of HBV infection (serology)
  • Characteristic arteriographic abnormalities not resulting fro noninflammatory disease processes
  • Biopsy of small- or medium-sized artery containing polymorphonuclear cells

Workup

• Definitive: Tissue biopsy
• Labs:
  • Cr, CK, LFT (elevated)
  • CBC (Leukocytosis, normochromic anemia, thrombocytosis)
  • Hepatitis serology
  • UA (proteinuria)
  • ESR/CRP
• Imaging
  • Angiography preferred: aneurysm or stenosis of medium-sized vessels
  • Arteriograms
  • CT/MRI
• To consider: CXR, blood cx, autoimmune serologic testing (ANCA, ANA, RF) to r/o other diseases

Differential Diagnosis

• Embolism, thrombosis, atherosclerosis
• HIV, Hepatitis, IE, mycotic aneurysm
• Fibromuscular dysplagia
• Microscopic polyangiitis, Wegener's, Chug-Strauss, IgA vasculitis, drug-induced vasculitis, connective tissue disease, SLE, cryoglobulinemic vasculitis

Management

• Rheumatology consult
• May warrant surgical intervention if abdominal involvement
• Corticosteroid:
  • Prednisone 1mg/kg
  • Methylprednisolone (7-15mg/kg, max 1000mg IV) for severe, organ threatening
• Immunosuppressive agent for moderate to severe
  • Cyclophosphamide (600mg/m2^{) q2weeks x 3 doses}
• ACEI or ARB for HTN

Sources

• Reference: Rosen's Emergency Medicine 8th edition. 2013. Chapter: Erythematosus and the Vasculitides. p1539-1540.
• Merkel PA, et al. Clinical manifestations and diagnosis of polyarteritis nodosa in adults. In: Post T, ed. UpToDate. Waltham, Mass.: UpToDate; 2014. www.uptodate.com. Accessed December 22, 2014.
• Merkel PA, et al. Treatment and prognosis of polyarteritis nodosa. In: Post T, ed. UpToDate. Waltham, Mass.: UpToDate; 2014. www.uptodate.com. Accessed December 22, 2014.
• Jacobs-Kosmin, D. (2014, Dec 12). Polyarteritis Nodosa. eMedicine. Retrieved 12/22/2014 from http://emedicine.medscape.com/article/330717-overview.