Friday, October 31, 2008

PAN versus MPA

Polyarteritis nodosa (PAN) and Microscopic polyangiitis (MPA) are two vasculitides which were previously grouped together.

However, they are currently thought of as two separate entities.

PAN is a vasculitis of the medium-sized arteries, sparing the smaller vessels and therefore does NOT cause a glomerulonephritis. Any renal compromise which results is generally due to ischemia from inflammation of the medium-sized renal vessels. PAN is often associated with hepatitis B infection.

In contrast, MPA is a vasculitis of the small-sized vessels, and therefore results in a pauci-immune glomerulonephritis. It is very commonly ANCA-positive.

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