Polyarteritis nodosa (PAN)

Polyarteritis nodosa is inflammation of medium-sized, and sometimes small, arteries, in which the immune system appears to attack vessel walls in a pattern of necrotizing vasculitis that can reduce blood flow to the tissues those arteries supply. Unlike some related vasculitis conditions, PAN typically does not involve ANCA antibodies or granuloma formation, and it preferentially affects the skin, peripheral nerves, and gastrointestinal tract.

It is rare, with a French population study estimating prevalence at roughly 31 cases per million adults, and that same research found the condition about twice as common in people of European ancestry. Cases were once frequently linked to hepatitis B infection, and while that association has declined substantially as hepatitis B rates have fallen, current research increasingly explores genetic and other contributing factors.

Common signs

Fever, fatigue, weight loss, muscle and joint aches, skin nodules, ulcers or a lacy purplish rash, numbness or weakness from nerve involvement, abdominal pain, and high blood pressure.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.