Case Presentation: A 28-year-old Middle Eastern male, previously diagnosed with Systemic Lupus Erythematosus (SLE) and biopsy-proven Lupus Nephritis at the age of 18 in Egypt, had been managing his condition with a daily dose of mycophenolate mofetil at 250 mg. During a routine clinic follow-up, laboratory tests were conducted, revealing concerning results. His 24-hour urine protein level had risen to a significant 2558 mg/24 hr, and his creatinine levels had increased to 2.1 mg/dl from a baseline of 1.12 mg/dl. In response to these alarming findings, the patient’s treatment plan was adjusted, and the dose of Cellcept was increased to 500 mg daily. However, much to the medical team’s surprise, despite the escalation of treatment, the 24-hour urine protein levels continued to climb, ultimately reaching 3941 mg/24 hr. In addition to this, the patient displayed persistent normal complement levels, negative results on double-stranded DNA testing, and anti-Smith antibodies measuring less than 0.2. In light of these perplexing findings, a kidney biopsy was deemed necessary to gain further insights into the underlying renal condition. The biopsy results were unexpected; they revealed concurrent Focal Segmental Glomerulosclerosis (FSGS) with no evidence of active lupus nephritis, challenging the initial diagnosis and treatment approach. Subsequently, the medical team decided to wean the patient off mycophenolate mofetil and initiated treatment with rituximab, as it became evident that the underlying renal complication was not lupus nephritis but rather FSGS.
Discussion: Systemic lupus erythematosus is a chronic autoimmune disorder marked by the production of autoantibodies targeting nuclear and cytoplasmic antigens, impacting multiple organs[1]. Nephrotic-range proteinuria often indicates proliferative lupus nephritis and/or membranous lupus nephritis. However, in rare cases, systemic lupus erythematosus patients with nephrotic syndrome may exhibit kidney biopsy results showing focal segmental glomerulosclerosis lesions [2]. This case report discusses the rare occurrence of Focal Segmental Glomerulosclerosis (FSGS) alongside Lupus Nephritis in an SLE patient.
Conclusions: The coexistence of FSGS with SLE and Lupus Nephritis poses a therapeutic challenge. Some patients may not respond to standard treatments, emphasizing the need for a repeat renal biopsy to establish an accurate diagnosis and provide personalized care. This case underscores the importance of renal biopsies in the management of SLE patients. While renal abnormalities in SLE patients are often attributed to lupus nephritis, this case highlights the necessity of considering alternative renal complications such as FSGS, which can coexist with lupus nephritis. Accurate diagnosis and precise assessment of disease activity are vital for tailored management.