Unmasking Focal Segmental Glomerulosclerosis in A Patient With Lupus Nephritis: A Rare Clinicopathological Overlap
Keywords:
Systemic lupus erythematosus, Lupus nephritis, Focal segmental glomerulosclerosis, Proteinuria, Renal biopsy, Rituximab.Abstract
Background
Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disorder in which lupus nephritis (LN) represents one of the most serious complications. Persistent nephrotic-range proteinuria despite appropriate immunosuppressive therapy should prompt consideration of concurrent renal pathology. Focal segmental glomerulosclerosis (FSGS) is an uncommon but clinically significant lesion that may coexist with lupus nephritis and adversely influence renal prognosis.
Case Presentation
A 28-year-old Middle Eastern male with biopsy-proven lupus nephritis diagnosed at the age of 18 years presented with progressively worsening nephrotic-range proteinuria despite maintenance therapy with mycophenolate mofetil (MMF). Laboratory evaluation revealed persistent proteinuria of 2.39 g/24 hours, serum creatinine of 2.5 mg/dL, normal complement levels (C3 and C4), negative anti-double-stranded DNA antibodies, and negative anti-Smith antibodies, suggesting inactive lupus disease. Owing to persistent renal dysfunction despite stable serological markers, repeat renal biopsy was performed. Histopathological examination demonstrated focal segmental glomerulosclerosis with intimal fibrosis and no evidence of active lupus nephritis. MMF was discontinued because of poor tolerance to higher doses, and treatment was modified with intravenous rituximab along with optimized supportive nephroprotective therapy. During follow-up, renal function remained stable without further clinical deterioration
Conclusion
This case highlights the importance of considering superimposed FSGS in patients with lupus nephritis who continue to exhibit persistent proteinuria despite apparent immunological remission. Repeat renal biopsy remains invaluable in differentiating active lupus nephritis from secondary glomerular pathology and facilitates individualized treatment decisions that may improve long-term renal outcomes.
