A Rare Case of IgA Postinfectious Glomerulonephritis in a Young Patient

Introduction: immunoglobulin A (IgA) dominant postinfectious glomerulonephritis (IgA PIGN) is a distinct clinical entity, very rare in the paediatric age group. It usually presents with severe renal failure, heavy proteinuria, hypertension, hypocomplementemia and frequently has an unfavourable prognosis. IgA PIGN generally occurs in association with staphylococcal infections and diabetes mellitus in adult patients. Other pathogens include Escherichia coli and Streptococcus sp. Immunofluorescence studies of renal biopsy specimens show IgA as dominant or codominant antibody.

Case Report: We encountered a 3 year old girl with IgA dominant PIGN that represented with acute renal failure, oedema, hypertension and heavy proteinuria of 7955mg/g creatinine. Renal biopsy specimen showed diffuse glomerular endocapillary hypercellularity with prominent neutrophil and monocyte infiltration on light microscopy. Strong deposits of IgA and C3 were observed along the glomerular basement membranes and the mesangium by immunofluorescence microscopy, and electron microscopy revealed the presence of subepithelial humps.

The patient was managed with steroid (and probatory antibiotic) therapy and is now on follow-up, showing a significant improvement after 6 months from the initial presentation (GFR and Cystatin C clearance 165ml/min/1.73m2 and 106ml/min/1.73m2, respectively). No signs of bacterial infection were detectable.

Discussion: This variant of IgA PIGN must be distinguished especially from IgA nephropathy (IgA deposits) and postinfectious glomerulonephritis (low C3). Other differential diagnoses include C3 glomerulopathy.

IgA PIGN is a recently identified disease entity that generally manifests in adult patients with both IgA deposits and low C3. We have presented a biopsy-proven case of IgA PIGN, manifesting at an exceptional young age and with good clinical outcome. To our best knowledge, this is the youngest IgA PIGN patient reported so far.