Dr Akshay Athavale1,2, Dr Veronica KY Cheung3, Professor David Gracey1,2
1Department of Renal Medicine, Royal Prince Alfred Hospital, Camperdown, Australia, 2Faculty of Medicine and Health, University of Sydney, Camperdown, Australia, 3Department of Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, Australia
Background
IgG4-related disease is a multi-system immune disorder characterised by formation of fibro-inflammatory lesions, commonly involving the pancreas, retroperitoneum, lymph nodes, salivary glands and kidneys. Diagnosis can be challenging, as clinical presentation and biochemical and radiologic investigations may be non-specific. We report a case of biopsy proven IgG4-related kidney disease with hallmark biochemical, radiologic and pathologic features.
Case Report
A 56-year-old man with IgG4-related disease was referred for investigation of worsening kidney function. IgG4-related disease was diagnosed three years earlier, following pancreatitis.
Investigations demonstrated a serum creatinine (sCr) of 110umol/L, estimated glomerular filtration rate (eGFR) 63mL/min. Twelve months before, sCr was 65umol/L, eGFR>90mL/min. Total serum IgG and IgG4 concentrations were markedly elevated at 41.58g/L and 10.56g/L, respectively. The C3 and C4 were low at 0.82g/L and 0.10g/L. Urine sediment was bland and 24-hour urine revealed 0.29g of proteinuria.
Contrast computed tomography demonstrated enlarged kidneys with rounded hypodense lesions in the cortex. Magnetic resonance imaging identified regions of severe diffusion restriction in both kidneys. Positron emission tomography demonstrated normal kidneys and no regions of abnormal glucose metabolism. Kidney biopsy confirmed IgG4-related disease, with storiform fibrosis and lymphoplasmacytic infiltrate, with large numbers of IgG and IgG4 positive cells. Treatment with oral prednisolone 40mg (0.6mg/kg) resulted in immediate improvement in kidney function (sCr 92 umol/L, eGFR 79 mL/min) and total IgG and IgG4 concentrations (13 g/L and 2.0 g/L respectively).
Conclusion
We present a case of biopsy proven IgG4-related kidney disease demonstrating characteristic radiologic and pathologic appearances, which may not correlate with disease severity. It is important that clinicians recognise these features on imaging and pathology, and consider IgG4-related disease as a possible diagnosis.
Biography:
Akshay is a final year advanced trainee in nephrology. He is also a Clinical Pharmacologist.