skip to main content

MPA — RACP Adult Medicine MCQ

Instant feedback + full explanation. One question, done properly.

ModerateRheumatologyMPARACP Adult Medicine

A 65-year-old woman presents with RPGN (creatinine 350 μmol/L), peripheral neuropathy (mononeuritis multiplex), and purpura. She has no ENT or pulmonary involvement. p-ANCA/anti-MPO is strongly positive. Renal biopsy shows pauci-immune crescentic GN. What is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Microscopic polyangiitis (MPA)

RPGN with pauci-immune crescentic GN, mononeuritis multiplex, purpura, and p-ANCA/anti-MPO positivity WITHOUT upper airway involvement is MPA. MPA affects small vessels and lacks the granulomatous inflammation of GPA. It predominantly affects kidneys (>90%) and peripheral nerves. Treatment is identical to GPA: rituximab or cyclophosphamide + prednisolone induction, then rituximab or azathioprine maintenance (MAINRITSAN trial: rituximab superior to azathioprine for maintenance).

Reference: ACR/EULAR – 2022 – AAV; MAINRITSAN Trial; eTG Rheumatology 2024