IgA crescentic glomerulonephritis in psoriatic arthritis - disease or treatment related?

Declining renal function was noted on monitoring in an asymptomatic 64 year old lady with psoriatic arthritis (PSA) diagnosed 1998 (eGFR 28 mL/min, UrinePCR 289 mg/mmol). Arthropathy was initially resistant to treatment, but remission was reached after 2008 with Adalimumab (Humira) 40 mg subcutaneous(SC) fortnightly; and methotrexate 15 mg SC weekly. Previous immunosuppression included Sulphasalazine (stopped 2016 as remission), Leflunomide (headaches), Infliximab (ineffective), Etanercept (transaminitis) and ciclosporin (ineffective). At eGFR 31 mL/min, Methotrexate, Adalimumab and Ramipril were discontinued. Infection, dehydration and urological causes were excluded (normal flexible cystoscopy, CT-KUB). In June 2023, she was admitted with uraemic symptoms, Pulse 112/min, BP 173/103 mmHg, O2 sat 96%. Investigations showed normochromic, normocytic anaemia, acidosis, hypocalcaemia and hyperphosphataemia, low transferrin with raised IgA 6.29 g/L. Other investigations were normal (ANA, ANCA, complement, light chains, electrophoresis, anti-GBM, blood / urine cultures, iron, ferritin, coagulation, viral screens). Renal biopsy showed glomerulonephritis and mesangial IgA and C3 deposition on immunohistochemistry, consistent with an active IgA nephropathy (diffuse proliferative and crescentic glomerulonephritis). Clinical Impression was anti-TNF-related IgA Nephropathy, CKD-related anaemia (treated with Darbepoeitin 50 mcg) and hypertension (controlled with Felodipine, Doxazocin, bendroflumethiazide). IV Methylprednisolone 1g daily × 3 and IV cyclophosphamide 950 mg with Mesna and Cotrimoxazole were started. She was discharged with Prednisolone 30 mg/day. Fourteen days later she had haematemesis, anaemia, with severe pyloric/duodenal ulcers requiring endoscopic adrenaline injections, IV pantoprazole and 3 units PRBC transfusion. After second cyclophosphamide, prednisolone 30 mg and darbepoeitin 50 µg were continued on discharge, BP 160/95 mmHg. Ten days later, she developed left hemiplegia and hemianaesthesia, BP 217/141 mmHg, GCS 14/15, NHSS score 18 with large right parietal intracranial haemorrhage. GCS dropped to 10/15, she underwent right decompression hemicraniectomy. She is currently rehabilitating, maintained on prednisolone 30 mg/day. The graph and table below indicate the course of renal functions and anaemia: This rapidly progressive crescentic IgA glomerulonephritis was likely secondary to Adalimumab, having excluded liver disease, viruses, myeloma, ma