What is Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN)?
Polyarteritis nodosa is inflammation of medium-sized arteries. It causes patchy damage wherever those arteries supply — nerves, skin, gut, kidneys and muscles — producing a characteristic mixture of weight loss, nerve damage, skin ulcers, abdominal pain and new high blood pressure. Unlike ANCA vasculitis, it does not affect the small vessels of the lung or cause glomerulonephritis.
Also called: PAN
Who gets Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN)?
It is uncommon, usually affecting adults between 40 and 60. A proportion of cases are associated with hepatitis B infection, which is why hepatitis serology is always checked — the treatment differs substantially when hepatitis B is the driver. ANCA is characteristically negative.
What are the symptoms of Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN)?
Not everyone has every symptom below, and having one does not confirm the diagnosis. These are the features that most often lead to assessment:
- Marked weight loss, fever, night sweats and severe fatigue
- Sudden foot drop or wrist drop, or patchy numbness and burning pain in different limbs
- Painful skin nodules, net-like purple mottling, or ulcers, usually on the legs
- Severe abdominal pain after eating, sometimes with bleeding
- New, sometimes severe, high blood pressure
- Muscle and joint pain
- Testicular pain
- Stroke, in a minority
How is Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN) diagnosed?
The pattern — systemic illness plus nerve damage in more than one limb plus skin or gut involvement — is the clue. ANCA is negative, which is diagnostically useful.
Nerve conduction studies map the pattern of nerve involvement. Biopsy of an affected nerve, muscle or skin lesion demonstrates the arterial inflammation and gives the diagnosis.
Angiography of the abdominal vessels may show the characteristic microaneurysms, particularly in renal and mesenteric arteries.
Hepatitis B and C serology are essential, since hepatitis B-associated disease is treated with antiviral therapy alongside a much shorter course of immunosuppression.
How is Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN) treated?
For disease not associated with hepatitis B: corticosteroids, with cyclophosphamide added for severe organ involvement, followed by maintenance with azathioprine or methotrexate.
For hepatitis B-associated disease: a short course of steroids, plasma exchange and antiviral treatment — prolonged immunosuppression here would worsen the underlying infection.
Blood pressure is controlled carefully, and nerve recovery is supported with physiotherapy, splinting and time. Nerve damage improves slowly over months and does not always recover completely.
Living with Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN)
Most patients achieve remission, and relapse is less frequent than in ANCA-associated vasculitis. Recovery from nerve damage is the slowest part and often the most limiting. Blood pressure and cardiovascular risk are monitored long-term.
When should you see a rheumatologist?
Unexplained weight loss and fever with a sudden foot drop, painful skin nodules or ulcers, or severe abdominal pain after eating needs urgent specialist assessment.
Common questions about Medium Vessel Vasculitis — Polyarteritis Nodosa (PAN)
How is PAN different from ANCA vasculitis?
PAN affects medium-sized arteries and is ANCA-negative. It does not cause the lung haemorrhage or glomerulonephritis typical of ANCA vasculitis, and it more often causes nerve damage, skin ulcers and gut involvement.
Why am I being tested for hepatitis B?
Because a proportion of PAN cases are driven by hepatitis B infection, and those are treated quite differently — with antiviral therapy and a short steroid course rather than prolonged immunosuppression.
Will my foot drop recover?
Nerve recovery is slow, taking months, and is often partial. Physiotherapy and splinting during that period preserve function and prevent contractures while the nerve regenerates.
This page is general information to support a consultation. It is not a diagnosis, and it does not replace an assessment by a doctor who has examined you.