Polyarteritis Nodosa
Polyarteritis nodosa (PAN) is a vasculitis that affects the small to medium sized vessels. It manifests in a variety of ways from a benign cutaneous form to a severe systemic type that can be fatal.
Clinical manifestations:
Systemic PAN is characterized by constitutional symptoms (e.g., malaise, fever, and weight loss), myalgia, arthralgia or arthritis, stomach pain, and numerous cutaneous manifestations. Other clinical symptoms include ischaemic heart disease, testicular discomfort, renal involvement (haematuria, proteinuria), hypertension, and neurological involvement (focal neurological deficits, hemiplegia, visual loss, mononeuritis multiplex). Since PAN can affect both small and medium-sized arteries, the skin symptoms may resemble those of Henoch-Schönlein purpura. However, the majority of skin characteristics associated with PAN indicates that the disease affects medium-sized arteries, including livedo reticularis, subcutaneous nodules, skin infarctions, and digital gangrene.
Cutaneous PAN affects only the skin. Patients may, however, present with a fever, myalgia, arthralgia, or arthritis. The involvement of the skin in cutaneous PAN is similar to that in systemic PAN; however there is no skin infarction. Cutaneous PAN is often associated with streptococcal infection.
EULAR/PRINTO/PRES classification of childhood polyarteritis nodosa*
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Criterion |
Definition |
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Histopathology |
Evidence of necrotizing vasculitis in medium or small-sized arteries |
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Angiographic abnormality |
Angiography - Conventional or Magnetic Resonance Angiography (MRA) or Computerised Tomography (CTA) - show aneurysm, stenoses or occlusion of a medium or small sized artery, not due to fibromuscular dysplasia, or other non-inflammatory causes. Conventional angiography is the preferred imaging modality. |
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Fulfil classification criteria: histopathology or angiographic abnormalities (mandatory) plus one of the five following criteria: |
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Livedo reticularis: purplish reticular pattern usually irregularly distributed around subcutaneous fat lobules, often prominent with cooling Skin nodules: tender subcutaneous nodules Superficial skin infarctions: superficial skin ulcers (involving skin and superficial subcutaneous tissue) or other minor ischaemic changes (nailbed infarctions, splint haemorrhages, digital pulp necrosis) Deep skin infarctions: deep skin ulcers (involving deep subcutaneous tissue and underlying structures), digital phalanx or other peripheral tissue (nose and ear tips) necrosis/gangrene |
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Muscle pain or tenderness |
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Systolic/diastolic blood pressure greater than 95th centile for height |
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Sensory peripheral neuropathy: neuropathy resulting in glove or stocking distribution of sensory loss Motor mononeuritis multiplex : Neuritis of a named peripheral nerve and only scored if motor involvement |
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Proteinuria >0.3 g/24 h or >30 mmol/mg of urine albumin/creatinine ratio on a spot morning sample Haematuria or red blood cell casts: >5 red blood cells/high power field or red blood cells casts in the urinary sediment or ≥2+ on dipstick Impaired renal function: measured or calculated GFR (Schwartz formula) <50% normal |
Resources to demonstrate mucocutaneous features of multi-system diseases are available.
Welcome to Skin Deep - Skin Deep (dftbskindeep.com)
https://www.nottingham.ac.uk/research/groups/cebd/resources/skin-of-colour/index.aspx
Investigation: There is no diagnostic blood test. Leukocytosis and thrombocytosis are common, as are elevated acute phase reactants (ESR or CRP). In contrast to ANCA-associated vasculitis disorders, ANCA are often negative in PAN.
Histopathological findings: Evidence of vasculitis in small to medium-sized arteries with fibrinoid necrosis. Renal manifestations usually arise from medium-sized vessel involvement (renal artery) and therefore glomerulonephritis picture in pathology is uncommon in PAN.
Imaging: Conventional angiography remains the gold standard. Aneurysms, perfusion abnormalities, and the presence of collateral arteries are indicators of arterial stenosis in radiography. MRA and CTA are non-invasive modalities that can be alternative investigations. MRA however, may miss small arterial stenosis or small aneurysms, while CTA carries a risk of radiation exposure.
Treatment: In systemic PAN, high dosage corticosteroid is used in combination with immunosuppressive medications such as cyclophosphamide during the induction phase and azathioprine during the maintenance phase. In patients who have not responded to conventional therapy, biologic agents such as anti-tumor necrosis factor (e.g., infliximab, adalimumab) have been used. In cutaneous PAN, NSAIDs, low to moderate dosage of corticosteroid are used. Other immunosuppressive agents are used with refractory disease (e.g., methotrexate, azathioprine, cyclophosphamide, and intravenous immunoglobulin). If there is an evidence of streptococcal infection, penicillin should be given. Some physicians advocate penicillin prophylaxis due to the high relapse rate as many cases are associated with streptococcal infection.
