A Case of IgA-Dominant Infection-Related Glomerulonephritis (IRGN)

Introduction: IgA-dominant IRGN is a rare immune complex–mediated glomerular disease associated with staphylococcal infections. It is often misdiagnosed as primary IgA GN or post-infectious glomerulonephritis (PIGN). Case Description: We report a case of a 72-year-old man presenting with lower limb edema and dyspnea. One month prior, he had MRSA bacteremia related to an indwelling port. He presented with AKI with creatinine of 2.07 mg/dl and 24h proteinuria 6.0 g. Imaging showed normal kidneys with no hydronephrosis. Biopsy revealed mesangial hypercellularity with severe podocyte injury. IF demonstrated dominant IgA and C3 deposition with lambda light chain predominance (Fig 1). EM showed mesangial and subepithelial “hump-like” electron dense deposits (Fig 2), confirming IgA-dominant IRGN. Despite targeted antibiotics therapy, renal function deteriorated with rise in creatinine to 5.5 mg/dL, prompting steroids initiation. Discussion: This case highlights the challenges in IgA-IRGN. Unlike classical PIGN with IgG-dominant deposits, IRGN is associated with IgA-dominant deposits. While infection eradication should be primarily tackled, the utility of immunosuppressive therapy remains controversial, especially in the setting of active infection. Further studies are needed to outline treatment plans and improve outcomes in this rare but serious disease.Diffuse Mesangial IF Positivity for IgA (2+), C3 (2+), and Lambda (2+) in IgA-Dominant IRGN.Figure 2. EM Showing Subepithelial Hump-Like Electron-Dense Deposit and Podocyte Foot Process Effacement in IgA-Dominant IRGN (Uranyl acetate and lead citrate x2600).