Abstract: TH-PO980
Chronic Inflammatory Demyelinating Polyneuropathy and Concurrent Membranous Nephropathy Associated with Anti-Contactin-1 Autoantibodies
Session Information
- Glomerular Trainee Case Reports
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 1602 Pathology and Lab Medicine: Clinical
Author
- Tarabzuni, Ola, Mcmaster, Hamilton, Ontario, Canada
Introduction
MN is a common cause of nephrotic syndrome in nondiabetic adults. CIDP is an acquired disorder of peripheral nerves. Antibodies directed against the paranodal axonal cellular adhesion molecule contactin-1 and its binding partner neurofascin have been identified in some severe cases of CIDP. Case reports of patients with co-existing MN and CIDP have been published, but an underlying disease mechanism has not been described in these patients
Case Description
A 45-year old male was diagnosed with CIDP in March 2015. He was treated with prednisone, IVIG and azathioprine with good response. In September 2016, he presented with nephrotic syndrome with 22 g/day of protein. He underwent a renal biopsy which showed stage 2 MN. Renal function was normal and anti- phospholipase 2 antibody was negative. Malignancy, infectious, and routine autoimmune investigations were negative. Additional serology was positive for IgG4 anti-contactin-1 antibody. Neurofascin antibody was negative. We examined renal tissue for the presence of contactin-1 antigen. The patient’s biopsy was strongly positive for this antigen, while 2 control were negative. Cyclosporine was added to the patient’s regimen with good resolution of proteinuria.
Discussion
Anti-contactin-1 antibodies have been identified as a cause of CIDP. This is the first report of these antibodies being identified in a case of secondary membranous nephropathy. Anti-contactin 1 antibody may be a novel diagnostic test in this condition.