Rheumatology for MRCPI Part 2

A 66-year-old man presents with 6 weeks of malaise, weight loss, epistaxis and nasal crusting, followed by haemoptysis. Creatinine has risen to 210 micromol/L and urine microscopy shows red cell casts. Chest CT shows bilateral cavitating nodules. c-ANCA with anti-PR3 specificity is strongly positive. What is the most appropriate initial treatment?

1. Long-term co-trimoxazole as the primary treatment Wrong as primary treatment, although co-trimoxazole is used for Pneumocystis prophylaxis during immunosuppression and has a limited role in localised upper airway disease.
2. High-dose corticosteroids with either rituximab or cyclophosphamide correct Correct. This is granulomatosis with polyangiitis with organ-threatening disease: upper airway, lung and glomerulonephritis. Remission induction requires high-dose steroids plus rituximab or cyclophosphamide, both of which are effective, with rituximab preferred in younger patients concerned about fertility and in relapsing disease.
3. Methotrexate monotherapy Wrong for this severity. Methotrexate has a role in non-organ-threatening disease and in maintenance, not in induction with progressive renal failure and pulmonary haemorrhage.
4. Corticosteroids alone Insufficient for organ-threatening vasculitis. Steroid monotherapy fails to induce durable remission and relapse is near-universal.
5. Broad-spectrum antibiotics and antifungal therapy for the cavitating nodules Understandable but wrong. Infection is a differential for cavitating nodules, but the ANCA positivity, glomerulonephritis and upper airway disease together make vasculitis the diagnosis, and delay costs nephrons.

The point: ANCA-associated vasculitis: PR3 with c-ANCA typically granulomatosis with polyangiitis; MPO with p-ANCA typically microscopic polyangiitis. Induce with steroids plus rituximab or cyclophosphamide, add plasma exchange in selected severe renal or pulmonary haemorrhage cases, then maintain. Give Pneumocystis prophylaxis.

Source: EULAR/ERA-EDTA recommendations for the management of ANCA-associated vasculitis EULAR · tier 2, specialty society or college