A SAN1, S CHANDLER1, RMILES1
1Greenslopes Private Hospital, Greenslopes, Australia
Background: IgG-4 related disease is a multisystem sclerosing disorder characterised by elevated IgG-4 levels, eosinophilia and Ig-G4 positive plasmacytic infiltration of various organs including kidneys, pancreas, thyroid, salivary glands and biliary tract. The most common renal manifestation is tubulointerstitial nephritis with sclerosis. Membranous nephropathy and proliferative glomerulonephritides may co-exist.
Case Report: A 54-year-old man was referred to the renal clinic in 2012 for multifocal T2 hyperintensities in the kidneys on PET/CT scan during his work-up for IgG monoclonal gammopathy. Past medical history included type 2 diabetes, hypertension and chronic sinusitis. Renal function was normal with serum creatinine 90 μmol/L without haemoproteinuria. Renal MRI confirmed numerous T2 low signal foci, thought to be lipid poor angiomyolipomata.Over five years he developed asthma, progressive sinusitis, profound lethargy, night sweats and low-grade fevers. In March 2018, he represented with serum creatinine of up to 160 μmol/L with nephrotic range proteinuria (urinary protein-to-creatinine ratio of 582 g/mol), hypoalbuminaemia (22 g/L), intermittent microscopic haematuria, marked eosinophilia (5.3 x 10*9/L), and elevated IgG (51g/L). Renal biopsy showed heavy interstitial infiltrate of a mixture of IgG-4 positive plasma cells and eosinophils with zones of collagenous sclerosis. The two glomeruli contained in the specimen were morphologically normal. The diagnosis of IgG-4 related disease was made and renal function recovered within five days of commencing steroid therapy.
Conclusion: IgG-4 related renal disease should be considered in patients presenting with renal parenchymal abnormalities in the presence of systemic symptoms, eosinophilia and elevated IgG. In this case, the urinary abnormalities were suggestive of co-existing glomerulonephritis. However this was not seen, likely due to sampling error. Excellent response to steroid therapy was achieved.
Aye San is a dual Advanced Trainee in Nephrology and General medicine at Greenslopes Private Hospital. She also hold the position of Chief Medical Registrar and Lecturer in Greenslopes Clinical Unit of University of Queensland.