case_images: PMC11218049_01
case_images: Kidney biopsy findings. a, b: The first kidney biopsy showed sclerotic lesions in the glomerular capillaries (arrow) near the vascular pole, and perihilar variant of focal segmental glomerulosclerosis was diagnosed (original magnification x 400). a: periodic acid Schiff stain; b: periodic acid methenamine silver (PAM)-Masson stain. c: PAM-Masson stain showed no significant findings in the other glomeruli (original magnification x 200). d: One glomerulus showed a severe sclerotic lesion with hyalinization (arrow) in the glomerular capillaries near the vascular pole (Masson trichrome stain; original magnification x 200). Masson trichrome staining showed strong red staining (small arrow) in the proximal tubules. e: One glomerulus showed partial sclerosis and epithelial cell proliferation (large arrow; PAM-Masson stain; original magnification x 200). f: Granular swollen epithelial cells (arrow), defined by enlarged tubular epithelial cells with coarse granules, were found in some distal tubules and collecting ducts (original magnification x 200). g: Electron microscopy revealed abnormal mitochondrial proliferation (arrow) in the podocytes. h: Electron microscopy revealed abnormal mitochondrial proliferation (arrow) in the proximal tubular epithelium.
case_images: CNCS-12-042-01.jpg
case_images: PMC11218049_01_CNCS-12-042-01.jpg
case_images: Figure1
case_images: The 16-year-old male patient underwent a first kidney biopsy because his serum creatinine (Cr) level was 0.73 mg/dL and urinary protein excretion (UP) was 0.6 g/day. 13 glomeruli were obtained; none was sclerosing, but 1 showed sclerotic lesions of the glomerular capillaries near the vascular pole (Figure 1a, b); there were no significant findings in the other glomeruli (Figure 1c). Of the 16 glomeruli obtained, 9 showed global sclerosis, 1 had a severe sclerotic lesion with hyalinization in the glomerular capillaries near the vascular pole (Figure 1d), and 1 had partial sclerosis and epithelial cell proliferation (Figure 1e). When we re-examined the light microscopy images of the kidney, we noticed that Masson trichrome staining showed strong, red staining in the proximal tubules (Figure 1d), a feature not usually seen in kidney biopsies from patients with end-stage renal failure. Granular swollen epithelial cells, which have been reported as a characteristic finding in mitochondrial nephropathy, were found in some distal tubules and collecting ducts (Figure 1f). Electron microscopy revealed abnormal mitochondrial proliferation in the podocytes (Figure 1g) and partial foot process effacement. Abnormal mitochondrial proliferation was also seen in the proximal tubular epithelium (Figure 1h).
case_images: Myocardial biopsy. a: Light microscopy of the myocardial biopsy showed muscle fibers with indistinct borders and somewhat lucent areas (arrow; hematoxylin and eosin (H & E) stain). b: Vacuolated muscle fibers areas (arrow) were seen (H & E stain). c: Electron microscopy showed abnormal mitochondrial proliferation between the fragmented muscle fiber bundles. d: In vacuolated muscle fiber areas, there was a decrease in the number of mitochondria (arrow) and muscle fibers.
case_images: CNCS-12-042-02.jpg
case_images: PMC11218049_01_CNCS-12-042-02.jpg
case_images: Figure2
case_images: Light microscopy showed muscle fibers with indistinct borders and somewhat lucent areas (Figure 2a) and vacuolated muscle fibers areas (Figure 2b). Electron microscopy showed abnormal mitochondrial proliferation between the fragmented muscle fiber bundles (Figure 2c). In the vacuolated muscle fiber areas, the number of mitochondria and muscle fibers was decreased (Figure 2d).