ABSTRACT
Introduction: With the increase of COVID-19 vaccinations, the development of nephrotic syndrome (NS) after vaccination is one of the new concerns. Most NS cases after vaccination are accompanied by minimal change, while others include focal segmental glomerulosclerosis (FSGS). Although an association between COVID-19 infection and collapsing FSGS has been reported especially in patients with APLO1 risk variants, no cases of childhood collapsing FSGS cases after COVID-19 vaccination have been reported up to now. Case Description: Twelve-year-old Japanese girl had been administered BNT162b2 (Pfizer/BioNTech) vaccine. Soon after that, edema had gradually appeared and 15 days after the injection, she was referred to our hospital because of severe edema. She did not have any past nor family history. Blood examination showed severe hypoalbuminemia (sAlb 1.4 g/dL) without kidney disfunction (eGFR 118.0 mL/min/1.73m2) or hypocomplementemia. Urinalysis showed severe proteinuria (urine protein/Cr 12.8 g/gCr) with hematuria, indicating nephrotic syndrome. Prior to treatment, collapsing FSGS was confirmed by kidney biopsy. Prednisolone (PSL) 60 mg/day was started according to the clinical guidelines for pediatric nephrotic syndrome. She had not achieved the complete remission 28 days after administration of PSL, and cyclosporine and lisinopril treatment was started. In addition, we administered two cycles of methyl prednisolone pulse therapy. Finally, she achieved the complete remission after 2.5 months treatment. Comprehensive genetic testing revealed no variant in genes causing steroid resistant NS or asymptomatic proteinuria. Discussion(s): The new onset of NS after vaccination, including COVID-19 vaccination, has been reported. The actual mechanism has not been clarified yet, but some immunological impact is reported to be associated the onset after the vaccination. Interestingly, this patient showed collapsing FSGS which is common as a secondary FSGS, especially in patients with the APOL1 risk variants suffered viral infection. Collapsing FSGS accompanied by COVID-19 infection had been reported to be associated with interferon activation or VEGF activation. Patients with collapsing FSGS after COVID-19 vaccination may have a common etiology.