Rapidly Progressive Glomerulonephritis Due to IgA Nephropathy in a Patient With a Large Renal Mass.

IgA nephropathy (IgAN) is a common primary glomerulonephritis characterized by the deposition of IgA immune complexes within the glomerular mesangium. IgAN can present with a wide range of clinical manifestations, ranging from asymptomatic hematuria to severe renal disease. This case describes a 67-year-old woman with a history of diabetes mellitus, hypertension, and obesity who presented with acute kidney injury and clinical manifestations of nephrotic syndrome. A renal biopsy confirmed the diagnosis of IgAN. Additionally, imaging studies revealed a large, complex renal mass, raising concerns for renal cell carcinoma. The IgAN was treated with high-dose corticosteroids; however, the patient opted for active surveillance of the renal mass rather than surgical intervention. This case highlights the complex clinical presentation of IgAN and the challenges associated with managing patients with both IgAN and renal mass.