Polyarteritis nodosa
Updates to Article Attributes
Polyarteritis nodosa (PAN) is a systemic inflammatory necrotising vasculitis that involves small to medium-sized arteries (larger than arterioles).
Epidemiology
PAN is more common in males and typically presents around the 5th to 7th decades. 20-30% of patients are hepatitis B antigen positive.
Associations
Clinical presentation
Patients can present with systemic and focal symptoms.
Non-specific systemic signs and symptoms are almost always present and include fever, malaise and weight loss.
Localised symptoms relate to ischaemia and infarction of affected tissues and organs. The most commonly involved vessels, are the renal arteries 1, with visceral involvement also considered relatively common. The pulmonary circulation is typically spared, although bronchial arteries may occasionally be involved.
Frequent sites of involvement are 3,5:
- renal: 80-90%, tends to be the prominent site and major cause of death
- cardiac: ~70%
- gastrointestinal tract: 50-70%
- hepatic: 50-60%
- spleen: 45%
- pancreas: 25-35%
- CNS complications: 20-45% 4
Pathology
Initially, there is transmural and necrotising inflammation of medium-sized arteries, mostly involving part of the circumference which causes weakening of the wall leading to microaneurysm formation and subsequent focal rupture. There is a predilection for branch points. Fibrinoid necrosis of vessels promotes thrombosis of vessels followed by infarction of the tissue supplied. Fibrous thickening and mononuclear infiltration occur at a later stage. Different stages of inflammation can occur in the same vessel at different points.
Markers
- pANCA: levels can correlate with disease activity
Radiographic features
CT
Routine contrast-enhanced CT may be entirely normal or may demonstrate focal regions of infarction or haemorrhage in affected organs.
Angiography (DSA / CT angiography)
Direct catheter angiography is far more sensitive to changes within small vessels, although a good quality CTA can also demonstrate changes. Findings include:
- multiple microaneurysms
- characteristic but not pathognomonic
- typically 2-3 mm in size but can be up to
1cm1 cm - in the kidneys, the microaneurysms typically involve the interlobar and arcuate arteries
- haemorrhage may be present due to focal rupture
- occlusion may be present
Treatment and prognosis
Polyarteritis nodosa is usually fatal if untreated, often as a result of progressive renal failure or gastrointestinal complications. Prompt treatment with corticosteroids and cyclophosphamide may result in remission, and a remission/cure can be achieved in 90% of patients 3.
History and etymology
It was initially described by Kussmaul and Maier in 1866.
Differential diagnosis
- consider other vasculitides such as
- microscopic polyangiitis: has a much more established association with ANCA and tends to affect smaller arterioles, capillaries and venules
- rheumatoid vasculitis
- systemic lupus erythematosus (SLE)
- Churg-Strauss syndrome
-</ul><h4>Clinical presentation</h4><p>Patients can present with systemic and focal symptoms. </p><p>Non-specific systemic signs and symptoms are almost always present and include fever, malaise and weight loss.</p><p>Localised symptoms relate to ischaemia and infarction of affected tissues and organs. The most commonly involved vessels, are the renal arteries <sup>1</sup>, with visceral involvement also considered relatively common. The pulmonary circulation is typically spared, although bronchial arteries may occasionally be involved.</p><p>Frequent sites of involvement are <sup>3,5</sup>:</p><ul>- +</ul><h4>Clinical presentation</h4><p>Patients can present with systemic and focal symptoms. </p><p>Non-specific systemic signs and symptoms are almost always present and include fever, malaise and weight loss.</p><p>Localised symptoms relate to ischaemia and infarction of affected tissues and organs. The most commonly involved vessels are the renal arteries <sup>1</sup>, with visceral involvement also considered relatively common. The pulmonary circulation is typically spared, although bronchial arteries may occasionally be involved.</p><p>Frequent sites of involvement are <sup>3,5</sup>:</p><ul>
-</ul><h4>Pathology</h4><p>Initially there is transmural and necrotising inflammation of medium-sized arteries, mostly involving part of the circumference which causes weakening of the wall leading to microaneurysm formation and subsequent focal rupture. There is a predilection for branch points. Fibrinoid necrosis of vessels promotes thrombosis of vessels followed by infarction of the tissue supplied. Fibrous thickening and mononuclear infiltration occur at a later stage. Different stages of inflammation can occur in the same vessel at different points . </p><h5>Markers</h5><ul><li>pANCA: levels can correlate with disease activity</li></ul><h4>Radiographic features</h4><h5>CT</h5><p>Routine contrast-enhanced CT may be entirely normal or may demonstrate focal regions of infarction or haemorrhage in affected organs. </p><h5>Angiography (DSA / CT angiography)</h5><p>Direct catheter angiography is far more sensitive to changes within small vessels, although a good quality CTA can also demonstrate changes. Findings include:</p><ul>- +</ul><h4>Pathology</h4><p>Initially, there is transmural and necrotising inflammation of medium-sized arteries, mostly involving part of the circumference which causes weakening of the wall leading to microaneurysm formation and subsequent focal rupture. There is a predilection for branch points. Fibrinoid necrosis of vessels promotes thrombosis of vessels followed by infarction of the tissue supplied. Fibrous thickening and mononuclear infiltration occur at a later stage. Different stages of inflammation can occur in the same vessel at different points. </p><h5>Markers</h5><ul><li>pANCA: levels can correlate with disease activity</li></ul><h4>Radiographic features</h4><h5>CT</h5><p>Routine contrast-enhanced CT may be entirely normal or may demonstrate focal regions of infarction or haemorrhage in affected organs. </p><h5>Angiography (DSA / CT angiography)</h5><p>Direct catheter angiography is far more sensitive to changes within small vessels, although a good quality CTA can also demonstrate changes. Findings include:</p><ul>
-<li>typically 2-3 mm in size but can be up to 1cm</li>- +<li>typically 2-3 mm in size but can be up to 1 cm</li>