CASE 168 (February 2020)
A 68-year-old man with a history of systemic arterial hypertension diagnosed more than 10 years ago, with apparently good control, presents progressive proteinuria, 350 mg/24h two years ago, 730 mg/24h one year ago and 1.6 g/24h in your last control. There is no hematuria. There is no history of diabetes. Serum creatinine: 1.2 mg/dL, BUN: 12 mg/dL. There is no dyslipidemia. Serum albumin: 3.8 g/dL. Negative or normal autoimmunity studies. Virus studies: negative. Protein electrophoresis: normal. There is no family history of kidney diseases. Body mass index: 26.
Due to persistent and increasing proteinuria, it is decided to take renal biopsy. Look at the images.
Figure 1. H&E, X100.
Figure 2. H&E, X400.
Figure 3. PAS, X400.
Figure 4. Methenamine-silver stain, X400. Capillary walls without evident alterations.
Figure 5. Masson's trichrome stain, X400.
Figure 6. Masson's trichrome stain, X400. Look at the vascular pole (or perihilar portion).
Figure 7. Masson's trichrome stain, X400. Look at the vascular pole.
Figure 8. EM: In this capillary the basement membrane, podocitary processes, slit diapraghm, and endothelium, have normal characteristics. Original magnification, X2,100.
Figure 9. Another image showing a capillary wall with normal ultrastructure, original magnification, X3,200.
Figure 10. Compare the podocyte that covers the basement membrane on the left side of the image in this capillary with a normal capillary. EM, original magnification, X3,200.
Figure 11. Loss of podocitary processes in this capillary. EM, original magnification, X3,500.
Direct immunofluorescence for IgA, IgG, IgM, C3, C1q, kappa, and lambda: Negative.
What is your diagnosis?