PMC8851205_01
Radiological evolution since admission (day 1), boluses of methylprednisolone (day 6), kidney biopsy (day 10), initiation of tocilizumab (day 19), initiation of rituximab (day 23) and hospital discharge (day 48). It shows subpleural peripheral reticular thickening of the middle fields, right basal field and lingula and interstitial alveolar opacities in the middle and lower fields of the right lung and lower fields of the left lung.
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COVID infection with a clear renal involvement: Plasma creatinine 3.94 mg/dl, eGFR (CKD-EPI): 16 ml/min/1.73 m2, microhematuria and moderate proteinuria (Table 1 ). Chest X-ray with bilateral interstitial pneumonia (Fig. 1 ).
Renal biopsy: 11 glomeruli, 3 were globally sclerosed. Five with minor congestive changes and 3 with extracapillary proliferation and cell crescent formation. Tubulointerstitial compartment with chronic and acute inflammation, 30% tubular atrophy, tubular thyroidization, and 30% interstitial fibrosis. No changes in medium size vessels, or thickening of the media layer of the arteries. No congophilic deposits. Direct immunofluorescence with slight granular mesangial deposit of C3+, without deposits of IgG, IgM, IgA or restriction of light chains.
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Thus a renal biopsy was performed 10 days after admission, with a clinical judgment of pauci-immune mixed extracapillary proliferative glomerulonephritis associated with ANCA with moderate chronic changes (Fig. 2 ).