Cryoglobulinemic and Membranous Glomerulonephritis in Sjogren Syndrome

Introduction: We present a case of concurrent cryoglobulinemic glomerulonephritis with vasculitis and membranous pattern immune complex glomerulonephritis in a patient with Sjögren syndrome. Case Description: A 62-year-old woman with Sjögren syndrome and angioedema presented with acute kidney injury (serum creatinine 1.9 mg/dL from baseline 1.0 mg/dL), hypoalbuminemia (2.8 g/dL), proteinuria (urine protein-to-creatinine ratio 6.62), and microscopic hematuria. Serologies revealed positive anti-Ro/SSA and anti-La/SSB antibodies, low C3 and C4 levels, and previously positive cryoglobulins. Hepatitis B and C serologies were negative.Renal biopsy demonstrated a membranoproliferative pattern with strong PAS-positive endocapillary hyaline thrombi, endocapillary hypercellularity, fibrinoid necrosis, and vasculitis. Immunofluorescence showed a full house pattern with polyclonal IgG, IgM, kappa, and lambda light chains, consistent with mixed cryoglobulinemia. Electron microscopy revealed mesangial, subendothelial, and segmental endocapillary deposits with microtubular substructures. Additionally, widespread subepithelial immune complex deposits distinct from cryoglobulin-associated deposits suggested a concurrent membranous pattern of injury. PLA2R was negative, and IgG1 subclass predominance supported a secondary autoimmune etiology. Immunosuppressive therapy with rituximab, mycophenolate mofetil, and corticosteroids was initiated. Renal function rapidly improved within 72 hours, and the patient was discharged to complete outpatient rituximab infusions and maintenance immunosuppression. Discussion: Multiple concurrent glomerular diseases can present in the setting of systemic autoimmune disease. The presence of two distinct immune complex patterns cryoglobulinemic vasculitis and membranous nephropathy underscores the diagnostic complexity and therapeutic implications.MPGN pattern of injury in glomerulus; vasculitis of artery with strong PAS positive deposit