Dr Rachel Frederick1, A/prof Kathleen Nicholls1,2, Dr Irene Ruderman1,2
1Department of Nephrology, Royal Melbourne Hospital, Melbourne, Australia, 2Department of Medicine, The University of Melbourne, Melbourne, Australia
Biography:
Rachel is dual training in nephrology and general medicine. Passionate about integrated patient care and clinical research, Rachel has a particular interest in dialysis decision-making, CKD pathways, and renal supportive care. Outside of medicine Rachel enjoys playing clarinet, singing in a choir and bushwalking.
Background:
IgG4-related disease is a rare systemic, fibroinflammatory disease, involving multiple organs that has a relapsing course. It is characterised by a lymphoplasmocystoid infiltrate and storiform fibrosis, often with eosinophilia and elevated IgG4 levels, although this is not universal.
Case Report:
We report a case of a 54-year-old female with a history of recurrent pancreatitis and sicca symptoms, presenting with Acute Kidney Injury (AKI), biopsy proven to be IgG4-related disease. The patient had an active sediment, nephrotic range proteinuria and eosinophilia. A renal biopsy demonstrated a IgG4 glomerulopathy (predominantly membranous distribution), with pseudocrescents. There was diffuse interstitial fibrosis with IgG4 positive plasma cells. Curiously the serum IgG4 had not been elevated, normal serum IgE levels and normal complement. The patient commenced prednisolone, and proteinuria improved, however, mental health side effects required a treatment change to rituximab. Bilateral Deep Vein Thromboses (DVT) and Pulmonary Embolisms (PE) were diagnosed investigating oedematous legs and subacute dyspnoea, despite a serum albumin greater than 29g/L. A Positron emission tomography (PET) scan did not demonstrate retroperitoneal fibrosis, or metabolically active IgG4 disease. Her serum creatinine improved over 1 month from a peak of 325umol/L to 185umol/L, and C Reactive Protein (CRP) from 70mg/L to 11mg/L.
Conclusions:
(1) AKI in the setting of recurrent pancreatitis and sicca symptoms should raise the suspicion for IgG4 disease. (2) Elevated IgG4 levels are not absolutely required for a diagnosis of IgG4 disease. (3) Monitoring biochemical response to treatment is more challenging when IgG4 is not elevated, but can consider CRP. (4) Rituximab can be used to treat IgG4-related disease.