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Microscopic polyangiitis with rapidly progressive glomerulonephritis — SCE Rheumatology MCQ

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ModerateVasculitisMicroscopic polyangiitis with rapidly progressive glomerulonephritisSCE Rheumatology

A 71-year-old woman with newly diagnosed microscopic polyangiitis has worsening renal function despite immediate initiation of remission-induction therapy with rituximab and a reduced-dose glucocorticoid regimen. Her serum creatinine has risen from 156 to 326 micromol/L over 8 days. Urine microscopy shows dysmorphic erythrocytes and red-cell casts. Kidney biopsy demonstrates pauci-immune necrotising crescentic glomerulonephritis, with cellular crescents in 60% of glomeruli and minimal interstitial fibrosis. MPO-ANCA is positive and anti-GBM antibodies are negative. CT of the chest shows no alveolar haemorrhage. She has bronchiectasis and required three courses of antibiotics for respiratory infections during the preceding year, but there is no evidence of current infection. Which is the most appropriate approach to adjunctive plasma exchange?

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Correct answer: A — Consider plasma exchange now after weighing renal benefit against infection risk

Explanation lettering: D = shown as A · E = shown as D · A = shown as E

This patient has rapidly progressive, organ-threatening ANCA-associated glomerulonephritis with potentially reversible renal injury: creatinine has risen rapidly to above 300 micromol/L, while biopsy shows predominantly active cellular crescents and little chronic damage. Current BSR guidance places this presentation within the group in whom plasma exchange may be considered, provided that potential benefit is weighed against adverse events. Her bronchiectasis and recurrent respiratory infections materially increase the importance of that individualised assessment because plasma exchange reduces 12-month end-stage kidney disease risk but increases serious infections. A is incorrect because the creatinine threshold prompts consideration, not mandatory treatment. B is incorrect because rapidly progressive renal disease is an independent setting in which plasma exchange may be considered; alveolar haemorrhage is not required. C is incorrect because dialysis dependence is not a prerequisite, and delay could allow additional irreversible nephron loss. E is incorrect because plasma exchange is not primarily a rescue intervention after waiting to establish failure of rituximab and glucocorticoids. If selected for severe renal disease, it should be considered during initial induction. The negative anti-GBM result is important because concomitant anti-GBM disease would provide a substantially stronger indication for prompt plasma exchange.

Reference: The 2025 British Society for Rheumatology management recommendations for ANCA-associated vasculitis (2025) — https://pubmed.ncbi.nlm.nih.gov/40499922/ The effects of plasma exchange in patients with ANCA-associated vasculitis: an updated systematic review and meta-analysis (25 February 2022) — https://pubmed.ncbi.nlm.nih.gov/35217545/