False-positive Serum Antiglomerular Basement Membrane Antibody due to Bovine Serum Albumin-containing Surgical Adhesive: A Case Report.

Antiglomerular basement membrane (GBM) disease has a poor prognosis. The rapid detection of serum anti-GBM antibody using an enzyme immunoassay, which has a high sensitivity and specificity, leads to an early diagnosis and improved prognosis. We report a case of acute kidney injury with false-positive anti-GBM antibody. A man in his early fifties underwent aortic arch replacement using bovine serum albumin (BSA)-containing surgical adhesion. After intravenous administration of vancomycin for a fever, he developed acute kidney injury without an abnormal urinalysis, and his anti-GBM antibody titer (fluorescence enzyme immunoassay [FEIA]) was 70.4 IU/mL. A kidney biopsy showed acute tubular injury and minor glomerular abnormalities without immunoglobulin G deposits, suggesting no evidence of anti-GBM glomerulonephritis. Consistent with the false-positive anti-GBM antibody test results, anti-GBM antibody determined using a chemiluminescent enzyme immunoassay was negative. A serum sample showed crossbinding to the FEIA plate from which the GBM antigen was removed. This finding indicated a nonspecific reaction to BSA, which contains a coating solution for the FEIA plate. This reaction was likely caused by anti-BSA antibody produced using BSA-containing surgical adhesion. Our findings suggest emerging challenges in diagnosing anti-GBM disease. Nephrologists must remain vigilant regarding false-positive anti-GBM antibody test results, particularly in cases evaluated with immunoassays that contain BSA.

A case of minimal change nephrotic syndrome complicated by Kimura disease treated with rituximab.

Kimura disease (eosinophilic granuloma of the soft tissue) is a benign granulomatous disease complicated by nephrotic syndrome. Herein, we report a case of recurrent minimal change nephrotic syndrome (MCNS) complicated by Kimura disease that was successfully treated with rituximab. A 57-year-old man presented to our hospital with relapsed nephrotic syndrome with worsening swelling of the right anterior ear and elevated serum IgE. MCNS was diagnosed on renal biopsy. Treatment with 50 mg of prednisolone rapidly placed the patient in remission. Therefore, RTX 375 mg/m2 was added to the treatment regimen, and steroid therapy was tapered. Early steroid tapering was successful, and the patient is currently in remission. In this case, the nephrotic syndrome flare-up was accompanied by worsening Kimura disease. Rituximab reduced the worsening of symptoms related to Kimura disease, including head and neck lymphadenopathy and elevated IgE levels. Kimura disease and MCNS may share a common IgE-mediated type I allergic condition. Rituximab effectively treats these conditions. In addition, rituximab suppresses Kimura disease activity in patients with MCNS, enables early tapering of steroids, and reduces the total dose of steroids.

Neuromyelitis Optica Complicated by Ornithine Transcarbamylase Deficiency Treated Safely with Pulse Steroid Therapy.

Steroid administration to patients with urea cycle disorders can cause hyperammonemia. We encountered a 36-year-old woman with neuromyelitis optica (NMO) complicated by ornithine transcarbamylase (OTC) deficiency. By reducing the doses of steroids and adequate infusion management, we were able to administer pulse steroid therapy without any severe complications. This case indicates the safety of steroid treatment in patients with urea cycle disorders.