A Rare Case of Granulomatous Interstitial Nephritis in a Patient With COVID-19-Associated Collapsing Glomerulopathy

ABSTRACT

Introduction: AKI in patients with COVID-19 is common. Among glomerular pathologies in COVID 19, COVID 19 Associated Collapsing Glomerulopathy (COVAN) remains the most common pattern of injury. AIN is a less common finding in patients with COVID-19. Reports of a subtype of AIN, granulomatous interstitial nephritis (GIN), among COVID-19 patients, are rare and have not been reported in association with COVAN. Here, we report a case of COVAN associated with severe GIN Case Description A 52YOM who presented with fever and fatigue. The physical exam was remarkable. The patient tested positive for COVID-19 and was found to have oliguric AKI with a creatinine of 9.6 mg/dl and nephrotic range proteinuria. Therefore iHD was initiated. Serologies and infection studies were negative. Fungal serologies were negative. A kidney biopsy revealed up to 32 glomeruli, four of which were globally sclerotic. Up to four glomeruli had features of glomerular collapse. The interstitium showed severe, diffuse edematous change with inflammatory infiltrates and focal interstitial granulomas. EM showed extensive foot process effacement and multiple TRI. Additional stains were negative. After the biopsy results returned, the patient was started on high-dose steroid. He experienced side effects with the high dose and therefore was transitioned to an every other day regimen. Losartan was added and prednisone taper was started. He was doing very well clinically at the last visit with resolving AKI and proteinuria Discussion: We have presented a rare case of GIN in a patient with COVAN. With negative infectious and autoimmune evaluation, it is possible the GIN was secondary to drug exposure and/or potentiated by the inflammatory mileu of COVID-19 infection. Even several years into the pandemic, we continue to find new kidney pathology among COVID-19. Kidney biopsy was absolutely necessary in this case and informed a dedicated treatment plan that allowed a remarkable recovery of kidney function.