Definition
• Systemic necrotizing immune complex–mediated vasculitis affecting small and medium-sized arteries of any organ
Clinical features
Epidemiology
• Rare disease affecting young adults but may also occur in children and older adults
• Male:female ratio, 2-3:1
• Associated with hepatitis B infection in 30% of cases
Presentation
• Nonspecific signs and symptoms: fever, abdominal pain, malaise, weight loss, myalgia, hypertension, melena, peripheral neuritis
• Most commonly involves, in descending order of frequency, kidneys, heart, liver, gastrointestinal tract
• Vasculitis in renal arteries; no glomerulonephritis
• Pericarditis, myocarditis
• Erythematous, tender nodules on extremities (usually lower)
• Cotton-wool spots; microaneurysms in retina
• Increased erythrocyte sedimentation rate
• No association with antineutrophil cytoplasmic antibody (ANCA)
• Pulmonary vessels as well as arterioles, venules, and capillaries are spared
• Diagnosis requires fulfilling three or more of the following diagnostic criteria (from Lightfoot RW Jr, Michel BA, Bloch DA, et al: The American College of Rheumatology 1990 criteria for the classification of polyarteritis nodosa, Arthritis Rheum 33:1088-1093, 1990):
• Weight loss of more than 4 kg since onset of disease unrelated to changes in diet or other factors
• Livedo reticularis (skin mottling on torso and extremities)
• Testicular pain or tenderness
• Myalgias or muscle weakness
• Mononeuropathy or polyneuropathy
• Diastolic blood pressure greater than 90 mm Hg
• Elevation of BUN (more than 40 mg/dL) or creatinine (more than 1.5 mg/dL)
• Positive serum hepatitis B surface antigen or antibody
• Abnormal arteriogram demonstrating occlusion or aneurysm of visceral arteries unrelated to atherosclerosis, fibromuscular dysplasia, or other noninflammatory causes
• Biopsy demonstrating neutrophils with or without mononuclear cells in vascular wall
Prognosis and treatment
• Fatal if left untreated
• Death usually occurs as a consequence of renal hypertension
• Complications include aneurysms (usually in gastrointestinal tract lesions) and thrombosis with consequent infarction
• Immunosuppressive agents: corticosteroids, azathioprine
• Cyclophosphamide
• Treatment with the previously mentioned agents leads to remission or a cure in 90% of cases
Pathology
Histology
• Leukocytoclastic vasculitis involving small to medium-sized arteries
• Multiple vasculitic lesions at different stages of development, often at branch points in different vessels or in the same vessel
• Acute lesions: segmental transmural fibrinoid necrosis with neutrophilic, lymphocytic, and eosinophilic infiltration
• Healing lesions: fibroblastic proliferation and nodular fibrosis
• Internal elastic lamina fragmented
• Lobular panniculitis surrounding affected vessels in skin
Immunopathology/special stains
• Not contributory
Main differential diagnoses
• Buerger disease: association with smoking
• Infectious endocarditis: infectious vasculitis; identifiable organisms in tissue sections or cultures
• Microscopic polyangiitis: vasculitic lesions are of the same age and involve smaller vessels, most cases associated with p-ANCA
Fig 1 Polyarteritis nodosa. Involvement of the fallopian tube: medium sized artery with prominent fibrinoid necrosis and transmural inflammation: low (A), medium (B), and high (C) power.
Fig 2 Polyarteritis nodosa. Vasculitic lesions of different ages (fibrinoid necrosis at left and intimal fibrosis at right) affecting the same vessel.
Fig 3 Polyarteritis nodosa. High power of older vasculitis lesion with intimal fibrosis and chronic inflammation.