Investigation

• raised ESR and/or CRP (this is non specific)
• normochromic, normocytic anaemia
• diagnosis is dependent upon histology or angiographic demonstration of microaneurysms in hepatic, renal or intestinal vessels. Biopsy of small arteries will show evidence of necrotising inflammation, and arteriography shows microaneurysms in the small-sized and medium-sized arteries of the kidneys and abdominal viscera (1)
• serological testing for hepatitis B, hepatitis C, and HIV should be carried out.
• ANCAs are negative in PAN, and a positive ANCA in the context of necrotising vasculitis strongly suggests an alternative (ANCA-associated) diagnosis (1)
• FDG-PET/CT is now a useful non-invasive imaging technique for diagnosis (2)

References

1. Polyarteritis Nodosa - a contemporary overview. U.S. National Library of Medicine 2016. Available from: https://pubmed.ncbi.nlm.nih.gov/26884100/

2. Fagart A et al 2022. Fluorodeoxyglucose positron emission tomography-computed tomography findings in a first series of 10 patients with polyarteritis nodosa. Available from: https://pubmed.ncbi.nlm.nih.gov/34302460/