Polyarteritis nodosa

Polyarteritis nodosa (PAN) is a rare systemic disease marked by inflammation and tissue death in medium-sized arteries throughout the body, typically affecting the vessels supplying the kidneys and internal organs while characteristically sparing the lungs' circulation. As a medium-vessel vasculitis, PAN destroys arterial walls and produces a distinctive imaging finding, small aneurysms strung like the beads of a rosary, which helps distinguish it from other forms of vasculitis. The disease can damage multiple organ systems through reduced blood flow. It is associated with hepatitis B or C infection in some cases, though the cause is unknown in many others. With treatment, five-year survival is around 80 percent; without treatment, only about 13 percent survive five years.