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Polyarteritis Nodosa

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Overview

Polyarteritis nodosa (PAN) is a rare vasculitis affecting medium-sized arteries with necrotising inflammation leading to aneurysm formation. It can affect any organ but it spares the pulmonary and glomerular arteries. The reason for this is unknown.

PAN is associated with hepatitis B infections

Epidemiology

  • Associated with hepatitis B, the incidence is higher where hepatitis B is endemic
  • More common in people aged 40-60 years
  • More common in men

Risk Factors

  • Hepatitis B infection
  • Age 40-60 years
  • Male adult

Presentation

The presentation of PAN is very non-specific, with predominant features being:

Other symptoms arise depending on what organs are affected:

  • Neurological:
    • Mononeuritis multiplex is the most common presentation
      • Sensory or motor impairments due to 2 or more nerves affected in different discrete areas of the body
  • Dermatological:
    • Livedo reticularis
    • Purpura
  • Renal:
  • Gastrointestinal:
    • Postprandial abdominal pain due to bowel ischaemia

Investigations

  • C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR):
    • Elevated
  • Hepatitis B surface antigen (HBsAg):
    • Positive in 30% of patients with PAN
  • Perinuclear-antineutrophil cytoplasmic antibodies (p-ANCA):
    • Negative, if these are positive, these suggest another form of vasculitis
  • Digital subtraction angiography (DSA), which may show:
    • Microaneurysms
    • Focal occlusive lesions in medium-sized vessels
  • Echocardiogram:
    • To exclude alternate diagnoses such as endocarditis
  • Small artery biopsy may be considered:
    • This may show necrotising inflammation

Management

Management involves using oral corticosteroids on a tapering regime with or without disease-modifying anti-rheumatic drugs (DMARDs)

Avoidance of hepatitis B infection and immunisation may reduce PAN associated with hepatitis B but does not eliminate PAN altogether

Complications

  • Renal involvement
  • Gastrointestinal tract involvement
  • Neurological involvement
  • Liver failure or hepatocellular carcinoma
  • Cardiovascular disease
  • Complications from immunosuppressive or corticosteroid therapy

Prognosis

  • Almost 50% of patients will die within 3 months from diagnosis if untreated, usually secondary to chronic kidney disease
  • Prognosis is worse with older age at presentation and renal CNS, or cardiac involvement

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