What is polyarteritis nodosa?
Polyarteritis nodosa (PAN) is a rare disease that
results from blood vessel inflammation ("vasculitis") causing injury to organ
systems. The areas most commonly affected by PAN include the nerves, intestinal
tract, heart, and joints. PAN can also affect the blood vessels to the kidney
resulting in high blood pressure and damage to kidney function.
What is vasculitis?
Vasculitis is a general term that refers to
inflammation of the blood vessels. When blood vessels become inflamed, they can
only react in limited ways. When inflamed, the blood vessel may become weakened
and stretch in size, which can lead to aneurysms, or become so thin that they
rupture resulting in bleeding into the tissue. Vasculitis can also cause blood
vessel narrowing to the point of closing off entirely so that organs become
damaged from loss of oxygen and nutrients that were being supplied by the blood.
PAN exclusively affects medium sized blood vessels.
What are the symptoms of PAN?
Because many different organ systems may be involved,
a wide range of symptoms are possible in PAN. Patients who have PAN may feel
generally ill and fatigued, have fevers, or have loss of appetite and weight.
They may have symptoms related to areas of involvement such as pain in the
muscles and/or joints, skin sores that may appear as hard tender nodules or
ulcers, abdominal pain or blood in the stools occurring as a result of
intestinal tract involvement, or shortness of breath or chest pain from disease
affecting the heart. High blood pressure is common in PAN and usually due to
vasculitis decreasing blood flow to the kidneys. PAN may affect nerves and cause
abnormal sensations, numbness or loss of strength. Any combination of these
symptoms may be present.
What causes PAN?
The cause of PAN is unknown. PAN is not a form of
cancer, it is not contagious, and it does not usually occur within families.
Evidence from research laboratories strongly supports that the immune system
plays a critical role in PAN, causing blood vessel and tissue inflammation and
damage. A form of vasculitis that mimics PAN can occur in people with hepatitis
B or C, so performing blood tests for these viruses is important.
Who is affected by PAN?
PAN can occur in people of all ages, from children to
the elderly and appears to affect men and women equally.
How is PAN diagnosed?
A doctor may suspect PAN based on information gathered
from a variety of sources, including: