A Case of NELL-1-Positive Membranous Nephropathy With Acute Kidney Injury Due to Bilateral Renal Vein Thrombosis.

Membranous nephropathy (MN) is a significant cause of nephrotic syndrome in non-diabetic adults. It can be primary, attributed to autoantibodies targeting podocyte antigens, or secondary to various disorders. Although rare, nerve epidermal growth factor-like 1 (NELL-1)-associated MN presents diagnostic and management challenges. Thrombotic complications such as renal vein thrombosis (RVT) are recognized but less reported, especially in NELL-1-positive MN. We report a 43-year-old male with NELL-1-positive MN complicated by acute kidney injury (AKI) due to bilateral RVT, treated successfully with thrombolysis. Histopathological analysis confirmed MN with specific immunohistochemical staining for NELL-1. Treatment included immunosuppressive therapy and tailored anticoagulation. This case emphasizes recognizing thrombotic complications in MN, particularly in NELL-1-positive cases. Further research is needed to explore serum anti-NELL-1 antibodies as biomarkers and optimal anticoagulation strategies in MN patients at risk of thrombotic events to improve outcomes and guide personalized management.