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Abstract: SA-PO671

A Challenging Case of C1q Nephropathy in a 62-Year-Old Man

Session Information

Category: Glomerular Diseases

  • 1302 Glomerular Diseases: Immunology and Inflammation

Authors

  • Alhosainat, Nidal, Rochester Regional Health, Rochester, New York, United States
  • Hunter, Nicole, Rochester Regional Health, Rochester, New York, United States
  • Choudhry, Wajid M., Rochester Regional Health, Rochester, New York, United States
Introduction

C1q nephropathy is a rare form of glomerulopathy characterized by mesangial deposition of the complement component C1q, usually affects older children and young adults. we are presenting an unusual case of a 62-year-old male patient with C1q nephropathy

Case Description

A 62-year-old man with PMHx of hypothyroidism, diabetes mellitus, admitted with shortness of breath and anuria for 24 hours. on presentation, BP was 104/70. Physical exam was notable for positive JVD, and lower extremity edema. Labs were significant for creatinine 4.82 mg/dl (baseline 1.8), Urinalysis showed RBC casts, +2 proteinuria. Urine protein:creatinine ratio was 821 mg/d. low C3 at 23mg/dl and C4 at < 5mg/dl. ANA, ANCA, RF, anti-RNP, anti-Smith, anti-SSA/SSB, anti-histone, anti-cardiolipin, CCP, myeloperoxidase, proteinase 3, cryoglobulin, SPEP, UPEP, immunofixation, HCV, and HIV all were negative.
Renal biopsy revealed proliferative glomerulonephritis with glomerular and extra glomerular IgG and C1q-containing immune complex deposits with organized substructure.
Diagnosis of C1q nephropathy was made and the patient was started on prednisone with significant improvement of the kidney function.

Discussion

C1q nephropathy is a poorly understood entity characterized by mesangial proliferation, and prominent C1q deposits on immunofluorescence microscopy in a patient with no clinical, laboratory or histopathological evidence of systemic lupus erythematosus (SLE).
The prevalence of C1q nephropathy varies from 0.2 to 16% and seems to be higher in children. Clinical presentation is diverse, and ranges from asymptomatic hematuria or proteinuria to frank nephritic or nephrotic syndrome.
Light microscopic features can mimic minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and proliferative glomerulonephritis. The main defining pathology is intense staining for C1q mainly in the mesangium, can be accompanied by IgG and IgM deposition.
Corticosteroids are the mainstay of treatment, with immunosuppressive agents reserved for steroid resistant cases. Poor outcomes can be seen if nephrotic syndrome and FSGS present.

Conclusion
C1q nephropathy is a distinct clinicopathologic entity characterize by mesangial C1q deposition, it may carry poor outcomes, therefore, early detection can be vital in the management, treatment usually by steroids, addition of immunosuppressive therapy might be required in resistant cases.