CASE 180 (February 2021)

Clinical information

A 5-year-old boy with no medical history presented edema of sudden onset. Laboratory tests showed proteinuria (80 mg/m2/h), dyslipidemia and hypoalbuminemia, with normal creatinine (0.4 mg/dl). On physical examination, systemic blood pressure was at the 95th percentile for his age, and urinalysis found 6 erythrocytes per high-power field, without leukocytes. Studies for autoimmunity and infections were negative. Treatment with prednisone was started and, given his blood pressure and microhematuria, a biopsy was ordered.

Due to logistical issues related to the COVID-19 pandemic, the kidney biopsy could only be done a month later. Look at the pictures.A .

Figure 1. H&E, X100. Normal appearance.

Figure 2. H&E, X400. Normal glomeruli.

Figure 3. H&E, X400.

Figure 4. PAS, X400.

Figure 5. Masson's trichrome stain, X400.

Figure 6. Methenamine-silver stain, X400. Normal capillary walls. Mesangium without alterations. Some enlarged podocytes.

Figure 7. EM, original magnification, X2,100. How are the podocyte processes?

Figure 8. EM, original magnification, X3,500. Identify podocyte processes and slit-diaphragm. Normal basement membranes in all capillaries.

Figure 9. EM, original magnification, X3,500. In the upper part of the capillary lumen there is a normal endothelial cell and in the lower part a lymphocyte is recognized. Identify pedicels (or podocyte processes) and slit-diaphragm.

Figure 10. EM, original magnification, X3,500. On the right the mesangium, with a mesangial cell; above a portion of the nucleus of a podocyte and towards the center and left, lower part, the lumen of a capillary.

Figure 11. EM, original magnification, X3,500. Two fragments of capillaries and between them the urinary space. Podocytic processes with normal characteristics.

Direct immunofluorescence for IgA, IgG, IgM, C3, and C1q: Negative.

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