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Rheumatoid Vasculitis — SCE Rheumatology MCQ

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HardRheumatoid ArthritisRheumatoid VasculitisSCE Rheumatology

A 55-year-old woman has a 20-year history of strongly RF- and anti-CCP-positive, erosive rheumatoid arthritis with rheumatoid nodules. Over 6 weeks she develops severe burning pain over the right lateral calf followed by right foot drop; 2 weeks later, numbness and weakness develop in the left ulnar distribution. Examination also shows periungual infarcts and a painful punched-out ulcer over the lateral malleolus. Nerve conduction studies demonstrate a multifocal, asymmetric axonal sensorimotor neuropathy. HbA1c and serum vitamin B12 are normal. What is the most likely cause?

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Correct answer: C — Rheumatoid vasculitis

The answer is rheumatoid vasculitis. The sequential involvement of anatomically separate peripheral nerves, producing foot drop and ulnar deficits, is mononeuritis multiplex. Its painful, asymmetric axonal pattern reflects ischaemic injury from inflammation of the vasa nervorum. Long-standing erosive, highly seropositive RA and concurrent periungual infarcts and a malleolar ulcer strongly support systemic rheumatoid vasculitis. Diabetic and vitamin B12 neuropathies are usually length-dependent and relatively symmetric, and the relevant tests are normal. Methotrexate can very rarely cause paraesthesia or weakness, but it does not characteristically produce this combination of mononeuritis multiplex and cutaneous ischaemia. Cervical myelopathy would cause central long-tract signs rather than a multifocal axonal peripheral neuropathy on nerve conduction studies.

Reference: Mertz P et al. Rheumatoid vasculitis in 2023: Changes and challenges since the biologics era. Autoimmunity Reviews. 2023;22(9):103391. https://pubmed.ncbi.nlm.nih.gov/40658239/