A Rare Renal Manifestation of Sjögren Syndrome: Membranous Nephropathy Meets Glomerulonephritis

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Introduction: Sjögren's syndrome is a chronic autoimmune disorder mainly affecting exocrine glands. Renal involvement occurs with variable frequency, with tubulointerstitial nephritis being the most common kidney manifestation. The pathophysiology linking Sjogren with renal diseases is poorly understood, with a limited number of case-reports available in the literature. Our abstract explores the rare but intriguing intersection of Sjogren syndrome and nephrotic syndrome, focusing on the specific association with membranous nephropathy and glomerulonephritis, and aims to highlight the complexities in diagnosis and management of these patients. Case Description: A healthy 33-year-old woman presented with a 5 day history of shortness of breath and anasarca. Labs showed nephrotic-range proteinuria (13.8 g), hypoalbuminemia, microscopic hematuria, low IgG, and normal renal function. Workup revealed only anti-RO/SSA-52 positivity. Renal biopsy demonstrated immune complex–mediated mixed focal proliferative and sclerosing glomerulonephritis (lupus-like Class III/V without C1q) and membranous nephropathy with granular IgG, kappa and lambda chains. Salivary gland US was suggestive of Sjögren’s syndrome. Treatment with IV methylprednisolone, tacrolimus, mycophenolate mofetil, diuretics, and IVIG led to improvement. Discussion: In Sjögren’s syndrome, immune complexes arise from autoantibodies, mainly ANA and anti-Ro/SS-A. Though membranous nephropathy is often idiopathic, autoimmune causes are recognized. Anti-Ro/SS-A and anti-La/SS-B antibodies support SS-related nephropathy. Usually, a MPGN pattern of glomerular injury is seen in an autoimmune etiology. In our case, due to its unique combination of both membranous and glomerulonephritis and biopsy suggestive of lupus-like features, it imposes a treatment dilemma. Treatment typically involves corticosteroids, immunosuppressants, and rituximab (in refractory cases), particularly with autoimmune etiologies, such as SS.Courtesy of David B. Thomas, M.D.

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