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PAN suspected — SCE Rheumatology MCQ

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ModerateVasculitisPAN suspectedSCE Rheumatology

A 48-year-old man presents with weight loss, livedo racemosa, postprandial abdominal pain and an asymmetric painful sensorimotor neuropathy consistent with mononeuritis multiplex. His blood pressure is 170/102 mmHg. C-reactive protein is markedly elevated, ANCA testing is negative, renal function is normal and urinalysis shows no haematuria or proteinuria. Which investigation is most appropriate to support the suspected diagnosis?

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Correct answer: A — CT angiography of the mesenteric and renal arteries

The correct answer is A. Livedo racemosa, mesenteric ischaemic pain, mononeuritis multiplex and severe hypertension without glomerular urinary abnormalities are characteristic of systemic polyarteritis nodosa, an ANCA-negative necrotising medium-artery vasculitis. CT angiography of the mesenteric and renal arteries can demonstrate characteristic microaneurysms, stenoses, occlusions or organ infarction and targets the vascular territories implicated by the presentation. Temporal artery biopsy evaluates suspected giant cell arteritis, which does not explain this pattern. Kidney biopsy is not preferred because PAN affects renal arteries rather than glomeruli. Nerve conduction studies may document mononeuritis multiplex but do not establish its vasculitic cause. Anti-dsDNA testing would support systemic lupus erythematosus, for which the clinical and urinary findings are not suggestive.

Reference: Chung SA et al. 2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Polyarteritis Nodosa, diagnostic testing recommendations, 2021. https://pubmed.ncbi.nlm.nih.gov/34235889/