Kidney Week

Abstract: FR-PO0951

A Case of Proliferative Glomerulonephritis with Monoclonal IgG Deposits in a Pediatric Patient

Session Information

• Pediatric Nephrology: Genetic Diseases, Development, Neonatal Nephrology, Glomerular Diseases, and More
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

• 1800 Pediatric Nephrology

Authors

• Boakye, Anita Amma Akomaa, Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States

Anita Amma Akomaa Boakye, DO

• Whitman, Abbie, Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States

Abbie Whitman, MD

• Phillips, Carrie L., Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States

Carrie L. Phillips, MD

• Nailescu, Corina, Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States

Corina Nailescu, MD

Group or Team Name

• Division of Pediatric Nephrology and Hypertesion at Riley Hospital for Children

Introduction

Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a rare disease of unknown etiology characterized by glomerular deposits of immunoglobulins. Few cases have been described in adult literature, with even fewer in the pediatric literature. Diagnosis is contingent on demonstrating a single heavy and light-chain isotype (most often IgG3). An appreciable number of patients experience persistent kidney dysfunction, with some progressing to end-stage kidney disease.

Case Description

A 5-year-old boy presented with 5 weeks of painless, intermittent, synpharyngitic gross hematuria. Examination showed old buttock lesions, normotension, and absence of obvious edema. UA showed nephrotic-range proteinuria (UPCR 5.88), pyuria, and microscopic hematuria with granular casts. Kidney function was preserved (Cr 0.43) with hypoalbuminemia (2.9 g/dL). Despite an ASO of 1,012 IU/mL, C3 and C4 were normal, and lupus evaluation (ANA, anti-dsDNA, anti-Smith) was negative.

Renal biopsy specimen showed diffuse acute proliferative glomerulonephritis with focal crescents. Immunofluorescence showed an almost full-house pattern (IgG, C3, C1q, kappa, lambda, and trace IgM), and electron microscopy showed subepithelial deposits with segmental membranous-like spikes. Nonlupus full-house nephropathy was considered, but the elevated ASO and clinical findings favored PSGN. Because the biopsy findings were unusual for PIGN, IgG subtyping and mass spectrometry were performed. This demonstrated granular mesangial IgG2 kappa deposits without substructure, confirming the diagnosis of PGNMID.

Discussion

PGNMID is a rare diagnosis whose symptoms overlap with common childhood GNs—its rarity and symptom overlap create diagnostic uncertainty. This case illustrates a diagnostic dilemma in which clinical and laboratory findings suggested a common cause of GN (PIGN or HSP nephritis), but discordant pathology broadened the differential diagnosis. The presence of a near-full house IF, in the absence of lupus serologies, further underscored the need to evaluate alternative diagnoses. Enhanced awareness of PGNMID in children better defines its clinical presentation, differentiates it from mimickers, and allows precise management of the disease. The case adds to the limited pediatric literature and underscores the need for heightened suspicion for PGNMID when evaluating pediatric GN.