A rare, but potentially life-threatening, disorder that causes inflammation of small and medium sized arteries. Blood supply to affected organs is slowed and this results in damage. Polyarteritis nodosa most commonly affects kidneys, nerves of the arms and legs, and the abdominal organs (bowel, liver, pancreas). Less commonly, the skin, heart, eyes, muscles, brain and reproductive organs can be affected. The average age of onset is 45 years and men are affected twice as often as women. PAN can be associated with chronic hepatitis B infection.