Late Recurrence of C3 Glomerulopathy After SARS-CoV-2 Infection in a Long-Term Kidney Transplant Recipient: A Case Report

BACKGROUND Kidney transplantation is the optimal treatment for end-stage kidney disease. Over the last decades, the long-term survival of renal allografts has significantly increased. Nevertheless, several causes, including the recurrence of native kidney disease, can impair the allograft function over time. C3 glomerulopathy (C3GN) is a rare disease, characterized by an abnormal activation of the alternative complement pathway that leads to the accumulation of C3 complement component in the glomeruli. C3GN frequently recurs after kidney transplantation during the first years, leading to graft failure. Recently, during the Covid-19 pandemic, the outcome of kidney transplant patients generally worsened, and several studies showed the effects of SARS-CoV-2 infection on renal function. CASE REPORT Here, we present the clinical case of a female kidney transplant recipient whose renal function worsened after 28 years of transplantation concurrently with two SARS-CoV-2 infections (in October 2020 and March 2022). In 1994, the patient received a diagnosis of acute post-infectious glomerulonephritis, leading to end-stage kidney disease and a living-donor kidney. The most recent allograft biopsy and laboratory test results showed chronic rejection and features of C3GN. Thus, given the possibility of a recurrent glomerulopathy, we reanalyzed the previous patient's renal biopsies performed in 1982 and 1988 and found that both suggested C3GN. CONCLUSIONS Based on these data and the current evidence, we could conclude that in this case, C3GN occurred as a late recurrence disease caused by complement activation after SARS-CoV-2 infection.