Part A: Clinical information
Gender, Age
Boy, 12 years old
Previous illnesses
Nephrotic syndrome that is steroid resistant
Time period since the onset of the first symptoms
Approximately 2 years
Presentation
Initial presentation: foamy urine; nephrotic range proteinuria with mild hematuria. No preceding event, no infectious disease. Renal function overall preserved. After initial treatment nephrotic range proteinuria recurred.
Laboratory parameters
Erythrocyturia and proteinuria. ANA/ANCA/anti-GBM negative.
Anti-PLA2R negative. No leucocyturia. Few casts.
Why was the decision made for a biopsy?
The persistent proteinuria in nephrotic range was the main reason for biopsy.
How long after the first symptoms was the biopsy conducted?
2 years
Suspected diagnosis of the indication for biopsy?
Minimal Change Disease / FSGS?
Note related to annotations: To avoid obscuring the lesions, the annotations are deliberately positioned close to, but not directly over, the lesion areas.
Part B: Kidney biopsy findings
Description of light microscopy:
Kidney biopsy mainly consistent of cortex with approximately 35 glomeruli. Only in some sections a single glomerulus with global glomerulosclerosis may be present, otherwise, most glomeruli show no apparent histological lesions. Capillary tuft contains normal capillary network; mesangial areas are in the background. There are no GBM (glomerular basement membrane) lesions; no influx of inflammatory cells or other active lesions. However, a closer look reveals prominence of podocytes in some glomeruli. Furthermore, few glomeruli contain small segmental lesions that are revealed to be tip lesions in deeper cuts. Tubulo-interstitium is well preserved: no IFTA (interstitial fibrosis and tubular atrophy), no inflammatory infiltrates. Few protein casts. IFTA < 5%. Vessels have no lesions.
Immunofluorescence:
no deposits of IgA, IgG, IgM, C3, C1q or kappa/lambda.
Electron Microscopy:
EM with an erythrocyte in the middle of the picture adjacent to well preserved endothelium. Podocytes show extensive obliteration of pedicles. No deposits. Findings are consistent for FSGS (focal segmental glomerulosclerosis).
Considerations:
Biopsy with FSGS, tip lesion variant. This variant has the best prognosis of all variants of FSGS. In children, steroid resistant nephrotic syndrome is closely associated with FSGS, but all variants may be present. Kidney biopsy shows well preserved tubulointerstitium which may add to a favorable prognosis. The findings by EM show the podocytopathy. They are very similar to findings in minimal change disease just serve to give additional proof of the podocytopathy, not to distinguish from minimal change disease.