Spontaneous Remission of Late Relapsing Membranous Nephropathy After Previous Immunosuppressant-Induced Remission: Case Report.

This is the first detailed report of spontaneous remission of late relapsing membranous nephropathy (MN) after previous immunosuppressant-induced remission. In March 2004, a 52-year-old Hispanic male presented with severe nephrotic syndrome with proteinuria of 13 g/24 h. The workup for infectious and autoimmune diseases was unrevealing. Renal biopsy showed MN (Stage II). A CT scan showed no malignancy but left pulmonary embolism and left renal vein thrombosis. Anticoagulation was started for asymptomatic thromboembolism. He achieved sustained complete remission of nephrotic syndrome after a prolonged, complicated treatment course of multiple immunosuppressants (corticosteroids and mycophenolate mofetil for 1 year, followed by alternating monthly corticosteroids and chlorambucil for 6 months, and again corticosteroids and mycophenolate mofetil for 6 years). Then in July 2021 (now at the age of 69 years), he developed nephrotic syndrome again with proteinuria of 6 g/24 h. Serological work-up was all negative except for the elevated serum Antiphospholipase A2 receptor (PLA2R) antibody at 42 RU/mL (nl < 14). Renal biopsy in November 2021 showed again MN (Stage III to IV). Immunohistochemistry staining of the biopsy tissue for PLA2R1 antigen was positive. A decision was made to observe him instead of starting immunosuppressants. He was treated with diuretics and Lisinopril. Anti-PLA2R antibody steadily improved to normal range and the nephrotic syndrome gradually improved and finally resolved by August 2023. There was no recurrence of nephrotic syndrome up to the most recent visit in March 2026. A review of the literature shows that a repeat biopsy in patients already known to have MN (especially those PLA2R-mediated cases) with relapse of nephrosis and stable renal function may not be necessary. In routine practice, the watchful waiting strategy for relapse of MN is less often taken as it should be. Therefore, more patients with relapsing MN deserve an observation period before starting immunosuppressants. Hopefully, KDIGO guidelines can include this point for relapsing MN.