Abstract: PUB334
A Unique Disease of C1q Nephropathy and Lymphadenopathy: Coincidence or Not?
Session Information
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Burkut Sarioguz, Ipek, Greater Houston Kidney Specialists, Houston, Texas, United States
- Merszei, Justin David, Greater Houston Kidney Specialists, Houston, Texas, United States
Introduction
C1q nephropathy,characterized by mesangial immunoglobulin and complement deposition with a predominance of C1q,represents a rare renal disease with a very low prevalence world wide varying from 0.2 to 2.5%.We present a case of a patient with a seven-year history of widespread lymphadenopathy who was referred for evaluation of Chronic Kidney Disease Stage 3.Renal biopsy unexpectedly revealed C1q nephropathy coexisting with diabetic nephropathy.
Case Description
A 59-year-old African American female, with a medical history of widespread lymphadenopathy,congestive heart failure,hypertension and type 2 diabetes mellitus,presented with CKD Stage 3.Despite,more than 10 years of follow-up by oncology for a possible B cell disorder,diagnostic workup,including bone marrow showed polyclonal B cell proliferation without definitive evidence of malignancy.Previous biopsy of lymph nodes demonstrated atypical lymphoid infiltrate.On first presentation,PR3 was positive without vasculitis symptoms.She had proteinuria 2694mg/gr with GFR 37ml/min and elevated sedimentation rate 86mm/h.ANA and RF were negative and C3,C4 were normal.A kidney biopsy showed immune complex mediated glomerulonephritis with strong C1q immunofluorescence with background of diabetic nephropathy.
Discussion
C1q complement deposition in the glomeruli suggests an immune complex mechanism underlying the disease process.However,the exact mechanism by which immune complexes selectively target renal mesangial cells remains uncertain.Given the common occurrence of false positive results for PR3 and the lack of clinical evidence supporting its significance in isolation,we chose not to rely solely on PR3 testing for diagnosis.B-cell activation may have resulted in glomerular immunoglobulin deposition and lympadenopathy, which allows binding of C1q to the Fc portion of the IgG antibodies;therefore rituximab, a monoclonal antibody targeting CD20 on B cells, was administered as a first-line treatment.Recent studies reported complete remission for patients with C1q nephropathy by using a single dose or two doses of rituximab.While rituximab is a well-established treatment for various autoimmune conditions,C1q nephropathy still presents a significant clinical challenge. Further research is needed to elucidate the mechanisms driving immune complex formation in such cases and to optimize therapeutic strategies for improved patient outcomes.