What are the stages of polyarteritis nodosa (PAN)?

Updated: Dec 03, 2018
  • Author: Dana Jacobs-Kosmin, MD, FACP; Chief Editor: Herbert S Diamond, MD  more...
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PAN is divided into subacute, acute, and chronic stages. In the subacute stage, infiltration of mononuclear cells becomes more prominent, while in the acute stage, polymorphonuclear neutrophils infiltrate all layers of the vessel wall. (See Etiology.)

In the chronic stage, fibrinoid necrosis of the vessels causes thrombosis and tissue infarction. Aneurysmal dilatations of the involved arteries, as large as 1 cm in size, are characteristic findings of PAN. Kidney lesions show predominant arteritis without glomerulonephritis; however, in patients with severe hypertension, glomerulosclerosis may be superimposed with glomerulonephritis. Pulmonary arteries are not involved, and bronchial artery involvement is uncommon.

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