A case of triple pathology: seronegative anti-glomerular basement membrane antibody-mediated glomerulonephritis and membranous nephropathy in a patient with underlying diabetic kidney disease

Anti-GBM antibody in a patient with diabetic nephropathy; all that glitters is not gold

We present the case of a 58-year-old male diabetic patient admitted to our department for a slight decrease in kidney function, with nephrotic range proteinuria, hematuria (16,000/ml) and positive anti-glomerular basement membrane antibodies. Kidney biopsy revealed diabetic nephropathy with no evidence of crescent formation or linear immunoglobulin deposits along the basement membrane. We discuss the various clinical settings involving positive anti-glomerular basement membrane in the absence of crescentic glomerulonephritis.

Clinical-Pathological Features and Outcome of Atypical Anti-glomerular Basement Membrane Disease in a Large Single Cohort

Background: Atypical cases of anti-glomerular basement membrane (GBM) disease had absent circulating antibodies but linear IgG deposits along GBM in the kidneys. Herein, we reported the clinical-pathological features and outcome of these rare cases.

Methods: Linear IgG deposit along GBM were examined by immunofluorescence on renal specimens, with exclusion of diabetic kidney disease. Circulating anti-GBM antibodies were tested by commercial ELISA assay. Clinical, pathological and follow-up data were retrospectively analyzed.

Results: From 2013 to 2018, a total of 60 patients were diagnosed as atypical anti-GBM disease. They had a male predominance, with an average age of 51.7 ± 15.6 years. Three (5.0%) patients had alveolar hemorrhage. Forty five percent of them presented with acute kidney disease. All patients had linear IgG deposit along GBM, some in addition on tubular basement membrane and/or Bowmans' capsules. C3 deposition was found in 65.0% of the patients. 41.7% (25/60) of the patients showed crescent formation and the percentage of crescent was (34.7 ± 23.5)% in those patients. They had higher prevalence of hematuria and C3 deposit, higher levels of serum creatinine, worse renal and patient survival than those without crescent (P < 0.05). During the follow-up of 35.7 ± 21.4 months, 14 (23.3%) patients progressed to ESRD. The serum creatinine on diagnosis [per 200 μmol/L increase, HR (95% CI): 2.663 (1.372, 5.172), P = 0.004], serum C3 [per 0.1 g/L increase, HR (95% CI): 0.689(0.483, 0.984), P = 0.040] and the intensity of kidney C3 staining [per 1+ increase, HR (95% CI): 2.770 (1.115, 6.877), P = 0.028] were independent predictive factors for kidney outcome. Nine (15.0%) patients died of all causes.

Conclusions: Atypical anti-GBM disease manifested milder kidney injury and scarce pulmonary hemorrhage compared to the classical cases. Though heterogeneous, a substantial number of the patients had complement activation and crescent formation. Patients having crescents presented with more severe clinical course and worse outcomes. The poor kidney and patient prognosis emphasize prompt interventions from physicians. The immunosuppressive intervention was not associated with kidney or patient outcome. Further studies are needed to address the optimal therapeutic regimen.

Coexistence of Anti-Glomerular Basement Membrane Glomerulonephritis and Membranous Nephropathy in a Female Patient with Preserved Renal Function

Renal prognosis for anti-glomerular basement membrane (GBM) glomerulonephritis is poor. The greater the amount of anti-GBM antibody binding the antigen (type IV collagen of the glomerular basement membrane), the greater the number of crescents that develop in glomeruli, resulting in progression of renal impairment. Immunofluorescence staining reveals linear IgG depositions on glomerular capillary walls. Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome in middle-aged to elderly patients. Immune complex is deposited in the sub-epithelial space of the glomerulus resulting in the development of a membranous lesion. Immunofluorescence staining reveals granular IgG depositions on glomerular capillary walls. Coexisting anti-GBM glomerulonephritis and MN are rare and, here we report a case of coexisting anti-GBM glomerulonephritis and MN with preserved renal function. There are some cases of coexisting anti-GBM glomerulonephritis and MN do not show severely decreased renal function. A 76-year-old Japanese woman presented with nephrotic syndrome, microscopic hematuria, and was positive for anti-GBM antibody. Kidney biopsy revealed linear and granular IgG depositions in glomerular capillary walls, crescent formations, and electron-dense deposits in the sub-epithelial space. She was diagnosed with anti-GBM glomerulonephritis and MN. Steroid and cyclosporine therapy achieved complete remission, and kidney function was preserved. In conclusion, coexisting anti-GBM glomerulonephritis and MN can have preserved renal function. IgG subclass of deposited anti-GBM antibody may be associated with the severity of anti-GBM glomerulonephritis. In addition, in the case of nephrotic syndrome with hematuria, we should consider the possibility of coexisting anti-GBM glomerulonephritis and MN.

Spectrum of renal disease in diabetes

The spectrum of renal disease in patients with diabetes encompasses both diabetic kidney disease (including albuminuric and non-albuminuric phenotypes) and non-diabetic kidney disease. Diabetic kidney disease can manifest as varying degrees of renal insufficiency and albuminuria, with heterogeneity in histology reported on renal biopsy. For patients with diabetes and proteinuria, the finding of non-diabetic kidney disease alone or superimposed on the changes of diabetic nephropathy is increasingly reported. It is important to identify non-diabetic kidney disease as some forms are treatable, sometimes leading to remission. Clinical indications for a heightened suspicion of non-diabetic kidney disease and hence consideration for renal biopsy in patients with diabetes and nephropathy include absence of diabetic retinopathy, short duration of diabetes, atypical chronology, presence of haematuria or other systemic disease, and the nephrotic syndrome.