Polyarteritis nodosa.

The first description of polyarteritis nodosa (PAN) was in 1852 by Karl Rokitansky, a pathologist at the University of Vienna. The initial report describes a 23-year-old man who had a 5-day history of fever and diarrhea. Since then, the definition of PAN has evolved. The currently accepted definition of PAN comes from the 2012 Chapel Hill Conference, which classified PAN as a necrotizing arteritis not associated with antineutrophil cytoplasmic antibodies of medium or small arteries without glomerulonephritis or vasculitis in arterioles, capillaries, or venules.