Atypical Presentation of Thin Basement Membrane Disease in a Child: Diagnostic and Management Considerations

Background: Thin basement membrane disease (TBMD) is a common cause of persistent hematuria and can be challenging to distinguish from other glomerular disorders due to overlapping clinical features. This case report highlights the diagnostic challenges associated with TBMD. Case Presentation: A 4-year-old boy was admitted for evaluation of abdominal pain and tea-colored urine following an appendectomy. Initial urinalysis revealed significant hematuria (red blood cell (RBC) count: 50-60/HPF). Additional findings, including proteinuria and maculopapular rashes, raised suspicion of Henoch-Schoenlein Purpura as a differential diagnosis. Despite treatment with corticosteroids and enalapril, recurrent hematuria persisted, particularly following upper respiratory infections. A renal biopsy demonstrated thinning of the glomerular basement membrane (GBM) (170 mm), which is a finding consistent with TBMD. Conclusions: We report a pediatric patient diagnosed with TBMD based on renal biopsy, who presented with recurrent hematuria. The diagnostic challenge in this case was due to the atypical extrarenal manifestations of TBMD, which initially suggested Henoch-Schonlein Purpura. However, as symptoms evolved, suspicion of Henoch-Schoenlein Purpura diminished. Ultimately, a biopsy was essential in establishing the final diagnosis. This case highlights the importance of considering TBMD in the differential diagnosis of glomerular hematuria, even when atypical features suggest alternative diagnoses.