Polyarteritis Nodosa

GENERAL PRINCIPLES

Epidemiology

Polyarteritis nodosa (PAN) affects men more than women, typically between the ages of 40 and 60 years. Most of the cases are idiopathic and a minority are caused by hepatitis B virus infection.

DIAGNOSIS

Clinical Presentation

• Most of the patients will have systemic symptoms such as fever, malaise, weight loss, arthralgias, and myalgias. Presentation may be nonspecific; it will depend on the organ systems affected. Some of the manifestations include the following:

î Skin: erythematous nodules, purpura, livedo reticularis, ulcers

î Renal: hypertension, perirenal hematomas, renal infarctions

î Neurologic: typically, mononeuritis multiples. CNS involvement is exceedingly rare

î Gastrointestinal: mesenteric arteritis leading to abdominal pain, melena, bloody or nonbloody diarrhea, and life-threatening gastrointestinal bleeding

î Cardiac: narrowing or occlusion of coronary arteries leading to myocardial ischemia and heart failure

î Musculoskeletal: myalgias and muscle weakness

î Reproductive: orchitis, testicular tenderness

î Ocular: ischemic retinopathy or optic neuropathy

• Limited cutaneous PAN is a term used for isolated skin involvement which rarely converts into systemic PAN. Isolated single-organ PAN can also occur; it is considered a monocyclic disease that rarely relapses.

Diagnostic Testing

• Laboratory findings, just like in other vasculitis, include anemia of chronic disease, and elevated ESR and CRP. A small percentage of patients may have eosinophilia. Hematuria may be present, but no active urine sediment and hepatitis serologies should be checked as well.

• Angiography, typically mesenteric, renal, or coronary, is often diagnostic. These demonstrate microaneurysms and/or stenoses in small to medium size vessels.

• Biopsy should be pursued whenever possible. Skin, nerve, muscle, or testicle biopsies may be easily accessible and provide diagnosis.

TREATMENT

• Glucocorticoids are considered first-line treatment. In patients with severe, life-threatening manifestations (creatinine gt; 1.5 mg/dL, cardiomyopathy, GI or CNS involvement), pulse intravenous methylprednisolone 1000 mg daily for 3-5 days is recommended. In patients without these manifestations, oral prednisone at 1 mg/kg is commonly started.

• Patients with severe manifestations or those with mild disease but unable to be tapered off steroids should be started on additional treatment. Cyclophosphamide is considered first line; if not tolerated or disease is resistant, other medications should be considered including rituximab, methotrexate, azathioprine, or mycophenolate mofetil.

• Hepatitis B-associated PAN treatment is based on the treatment of the infection with antivirals. Patients with severe manifestations can be started on glucocorticoids and plasma exchange until antiviral therapy becomes effective.