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Necrotizing inflammation of medium sized arteries and vasculitis.
Preferentially located at vessel bifurcations, resulting in microaneurysm formation, aneurysmal rupture with hemorrhage, thrombosis, and, consequently, organ ischemia or infarction
Tissue ischemia that occurs from polyarteritis can affect any organ including the skin, musculoskeletal system, kidneys, G.I. tract, cardiovascular and nervous systems.
Generally affects multiple systems and has protean manifestations, but most commonly affects skin, joints, peripheral nerves, the gut, and the kidney.
Multiple aneurysmal dilatations up to 1 cm in diameter, involving bifurcations and branches of small and medium sized arteries.
Inflammation may start in the vessel intima and progress to include the entire arterial wall.
It may destroy both the internal and external elastic lamina, resulting in fibrinoid necrosis.
Aneurysms develop in the weakened vessel.
Thrombi may develop at the site of the lesions.
Spares large vessels (the aorta and its major branches), the smallest vessels (capillaries and small arterioles), and the venous system.
Polyarteritis nodosa is often primary, however in adults it may be associated with infection such as hepatitis B infection or hematologic malignancy.
Three of the following 10 criteria must be present to classify aa periarteritis:
Weight loss of 4 kg or more
Livedo reticularis
Testicular pain/tenderness
Myalgia or leg weakness/tenderness
Mononeuropathy or polyneuropathy
Mononeuritis multiplex occurs in 60% of patients with polyarteritis nodosa.
Diastolic blood pressure greater than 90 mm/Hg
Elevated BUN and creatinine levels
Infection with hepatitis B virus (HBV)
Abnormality on arteriography
Biopsy of small- or medium-sized artery containing polymorphonuclear neutrophils.
Usually presents in middle age or later, but can appear in childhood.
Diagnosis is challenging because frequently presents as a nonspecific process, and organ involvement and disease severity are highly variable.
The pathogenesis is unknown.
Associated with viral infections, especially HBV.
The recessive loss of function mutations of ADA2 encoding gene, a growth factor, is the major extracellular adenosine deaminase that can cause polyarteritis vasculopathy (Elkan PN et al),
Cutaneous polyarteritis nodosa, is a rare form of vasculitis in small to medium sized arteries restricted to the skin.
Cutaneous polyarteritis nodosa lesions may include: subcutaneous nodules, livido reticularis purpura and ulcers, mainly on the lower extremities with no internal organ involvement.
Cutaneous polyarteritis nodosa with retiform purpura can be first manifestation of the disease.
Mesenteric arteritis due to polyarteritis manifests as abdominal pain after eating, and causes mesenteric ischemia.
Treatment:
The treatment for Polyarteritis nodosa usually involves using immunosuppressive medications to control the immune system and prevent further damage.
Treatment involves medications to suppress the immune system, including prednisone and cyclophosphamide.
When present, underlying hepatitis B virus infection should be immediately treated.
In PAN not associated with a hepatitis virus: prednisone and cyclophosphamide therapy.
In case of emergency, plasmapheresis may be tried
In PAN associated with a hepatitis virus: combination therapy of prednisone along with a virustatic, such as lamivudine (Hepatitis B) or interferon-alpha and ribavirin (Hepatitis C)
In some cases, methotrexate or leflunomide and rituximab may be helpful.
Corticosteroids are often prescribed initially to reduce inflammation and swelling.
Other drugs that may be prescribed include immunosuppressants like cyclophosphamide, azathioprine, and mycophenolate mofetil, that can help reduce inflammation, prevent blood vessel damage and limit the progression of the disease.
Treatment for periarteritis nodosa may also include specific interventions for some of the symptoms: pain relief medication, blood pressure medication, anticoagulants, and dialysis if the kidneys are severely affected.
Medications that suppress the immune system form the foundation of treatment for PAN. There are a variety of immunosuppressive medications that are used in PAN, each of which has individual side effects.
In people who have a PAN-like vasculitis that is associated with hepatitis B, antiviral medications used to treat the hepatitis form an important part of care.
Therapy results in remissions or cures in 90% of cases.
Untreated, the disease is fatal in most cases.
Associated conditions generally involve the kidneys and gastrointestinal tract, with gastrointestinal bleeding, infection, myocardial infarction, and/or kidney failure.
In case of remission, about 60% experience relapse within five years.
In cases caused by hepatitis B virus, however, recurrence rate is only around 6%.