La utilidad de las biopsias renales post mortem en la pandemia por SARS-CoV-2

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Abstract

Background: Renal involvement in patients with COVID-19 has been identified as a marker of poor prognosis, but its underlying mechanisms remain partially understood. Objective: Evaluate the histopathological findings in renal samples obtained by post-mortem percutaneous Tru-Cut® biopsy in deceased COVID-19 patients, in order to characterise renal involvement in this disease. Methods: Descriptive observational study of post-mortem renal samples obtained by ultrasoundguided percutaneous puncture in patients deceased from COVID-19 in the intensive care unit (ICU) and hospital ward (HW) (n = 19). Samples were analysed using light microscopy, immunohistochemistry (IHC), and transmission electron microscopy (TEM). Results: In the glomerular compartment, 50,0 % of patients showed glomerular sclerosis, and 50,0 % of those with diabetes exhibited diabetic nephropathy (Tervaert class III); one patient had focal segmental glomerulosclerosis. In the tubulointerstitial compartment, 53,0 % showed acute tubular necrosis (ATN), and 20,0 % had chronic tubular injury with interstitial fibrosis. Erythrocytes in tubules were observed in 63,0 % of ATN cases. In the vascular compartment, 60,0 % showed myointimal hyperplasia and 44,0 % arteriolar hyalinosis, with no evidence of vasculitis or thrombosis. TEM revealed particles consistent with SARS-CoV-2 virions in endothelial cells in 4 of 6 cases (66,7 %), and in all cases, tubular cell lysis, podocyte foot process effacement, and glomerular and peritubular microthrombi with endothelial damage. Conclusions: Post-mortem renal biopsies in COVID-19 revealed acute tubular injury, microangiopathy, and endothelial viral particles. These findings suggest a combination of direct viral cytopathic effect and endothelial dysfunction. This technique proved useful for investigating renal involvement in emerging diseases.