Abstract: TH-PO952
IgG-4 Positive Linear Deposition Anti-Glomerular Basement Membrane Nephritis with Negative Glomerular Basement Membrane Antibody (GBM Ab)
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
- 1202 Glomerular Diseases: Immunology and Inflammation
Authors
- Naranjo, Felipe Sebastian, Johns Hopkins Hospital, Baltimore, Maryland, United States
- Lohani, Sadichhya, Johns Hopkins Hospital, Baltimore, Maryland, United States
- Kiljanek, Lukasz, MedStar Shah Medical Group, Hollywood, Maryland, United States
- Gu, Xin, Louisiana State University, Shreveport, Louisiana, United States
- Choi, Michael J., MedStar Georgetown University Hospital, Washington D.C, District of Columbia, United States
Introduction
Anti-glomerular basement membrane (anti-GBM) nephritis is an antibody mediated small vessel vasculitis usually caused by IgG antibodies with predominance of IgG1 and IgG3 directed against basement membrane antigens.
Case Description
22 years old morbidly obese male with history of asthma, recurrent ear infections requiring Eustachian tubes, smoking and exposure to polyvinyl chloride, presented with 3 months of fatigue and was found to have proteinuria on urinalysis. He denied fever, chills, chest pain, cough or hemoptysis, abdominal pain, melena, arthralgias, edema, dysuria, hematuria or tea-colored urine. On physical exam, he was afebrile with stable vital signs and absence of sinus tenderness, lymphadenopathy, synovitis, rash and edema. Chest, cardiovascular and abdominal exam were unremarkable. 24-hour urine protein was 3.8g and albumin was 2.4g. Urinary sediment showed red cell casts. Labs showed a serum creatinine: 1-1.2mg/dl, serum albumin 3.7g/dl, HbA1c 5.2% and negative anti-DNA, ANA, cANCA, pANCA, PR3, MPO, anti-GBM, RF, Jo-1, cryoglobulins, HIV, HBV, HCV, SPEP and UPEP. Serum complement levels and free light chains ratio were normal. Renal ultrasound showed normal size kidneys. Chest CT showed scattered pulmonary nodules < 5 mm. Renal biopsy showed proliferative glomerulonephritis with 2/17 glomeruli with crescents and positive linear reaction for IgG4 along the GBM in immunofluorescence and foot process effacement in electron microscopy. He was started on prednisone 80mg and cyclophosphamide 2.5mg/kg/d; plasmapheresis was not done due to negative anti-GBM titers. Few months later he was started on lisinopril 40mg. After 19 months of treatment, 24-hour urine protein decreased to 0.14g.
Discussion
Usually anti-GMB nephritis presents as rapidly progressive GN rather than with nephrotic range proteinuria. Patients with deposition of IgG on the GBM on immunofluorescence and negative for circulating antibodies by conventional assays, may be positive when tested by highly sensitive biosensor assays. In anti-GBM disease, IgG1 and IgG3 subclasses are the usual antibodies but rarely IgG4 as these antibodies may not be detected on routine assays. Patients with diabetic nephropathy may present with linear IgG but should not have crescents or cellular casts as noted in our patient.