Kidney Week

Abstract: FR-PO0937

Macroscopic Hematuria in an Adolescent with ADPKD: A Rare Coexistence with IgAN

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

• Cocchi, Valeria, Medica Uruguaya, Montevideo, Uruguay

Valeria Cocchi, MD

• Spangenberg, Lucia, Pasteur Institute, Montevideo, Uruguay

Lucia Spangenberg, PhD

• Corvo, Ileana, Universidad de la Republica Uruguay, Montevideo, Uruguay

Ileana Corvo, MD, PhD

• Facal, Lucia, Medica Uruguaya, Montevideo, Uruguay

Lucia Facal, MD

• Auchayna, Maria, Hospital de Clinicas Doctor Manuel Quintela, Montevideo, Uruguay

Maria Auchayna, PhD

• Yandian, Federico, Medica Uruguaya, Montevideo, Uruguay

Federico Yandian, MD

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive renal cyst formation. Although macroscopic hematuria is a recognized complication, its coexistence with primary glomerular diseases such as IgA nephropathy (IgAN) is exceedingly rare, particularly in pediatric patients.

Case Description

A 13-year-old obese male with ADPKD (heterozygous PKD1 variant; c.5014_5015del, p.Arg1672fs), and a paternal family history of polycystic kidney disease presented with preserved renal function and normal blood pressure.. One week after amoxicillin-treated pharyngotonsillitis, he developed painless gross hematuria; urinalysis showed hematuria, red blood cell casts, sterile culture. Laboratory revealed normal renal function and complement levels, elevated ASO titers. Ultrasound was unchanged. Hematuria resolved spontaneously but recurred at 1 and 3 months, within mucosal infections. Persistent microhematuria and low-grade proteinuria (protein-to-creatinine ratio ~0.2 mg/mg) were noted. Given the atypical pattern, a kidney biopsy was performed. Histopathology revealed IgAN (Oxford M0E0S1T0C0). Immunofluorescence microscopy showed intense mesangial IgA deposition with moderate kappa and lambda light chains and mild IgM, without IgG, C1q, or C3. Electron microscopy demonstrated mesangial and subendothelial electron-dense deposits with focal podocyte foot process effacement.

Discussion

This case underscores the critical role of kidney biopsy even in the presence of a confirmed genetic diagnosis, particularly when the clinical phenotype is atypical or not fully explained by the underlying genetic disorder. To date, only two cases describing the coexistence of polycystic kidney disease and IgA nephropathy have been reported; however, neither included genetic confirmation of mutations in PKD-associated genes. Our case expands the current literature by providing genetically confirmed ADPKD associated with biopsy-proven IgA nephropathy, highlighting thel possibility of dual pathology and its implications for diagnosis and management.
Conclusions:
In patients with ADPKD, kidney biopsy remains essential for an accurate diagnosis when clinical findings are atypical. It can meaningfully influence management and prognosis and, when indicated, may be performed safely in specialized reference centers—even in the setting of polycystic kidneys.