Polyarteritis Nodosa (kidney)

This end stage kidney still shows active PAN with inflammation and fibrinoid necrosis of arterial walls.

This magnification reveals the extensive infiltrate to be composed of polymorphonuclear leukocytes. The vascular involvement is fully circumferential.

This vasculitis (PAN) affects small or medium-sized arteries. It often involves renal and other systemic viscera but usually spares the pulmonary arteries. Clinical manifestations may be acute, subacute, or chronic and the disease most often occurs in the age group 40-60 years. Renal involvement is often a cause of death. Because PAN does not involve capillaries and arterioles, glomerulonephritis does not develop. Hypertension is frequent as is peripheral neuritis. The disease can occur as a complication of hepatitis B or C; 10-45% of PAN patients are positive for HbsAg. The presence of antineutrophil cytoplasmic antibodies (P-ANCA or C-ANCA) is less frequent than in microscopic polyangiitis or Wegener disease. Steroids and cyclophosphamide are used in therapy but special consideration must be given when HbsAg is present.