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What is Polyarteritis Nodosa (PAN) typically involves which of the following? and explain in detail?
Ans (b) Small- or medium-sized muscular arteriesRef: Robbiris pathology 9th ed. 1506-507* PAN typically involves small- to medium sized muscular arteries. In contrast, large arteries and the aorta are involved in Takayasu arteritis.* Small arteries and arterioles are involved in a number of other diseases, including systemic lupus erythematosus.* Active lesions in PAN demonstrate a neutrophilic infiltration of the involved vessel wall with thrombosis and segmental,fibrinoid necrosis. Intermittent healing produces fibrosis of the- arterial wall and intimal thickening, which may lead to obstruction and infarction.* Aneurysmal dilations may arise as a result of asymmetrical involvement. Although the lesions in PAN resemble other immune mediated vascular lesions, the exact etiology of the disorder has not been elucidated.* PAN generally affects middle-aged men and has a poor prognosis, although steroids may be beneficial.