Laboratory Performance on Reporting Monoclonal Gammopathy During Cerebrospinal Fluid Oligoclonal Banding Analysis from External Quality Assessment Surveys

Objective Cerebrospinal fluid (CSF) oligoclonal banding (OCB) analysis is a sensitive test used to mainly aid multiple sclerosis (MS) diagnosis. Monoclonal gammopathy is usually an incidental finding during CSF OCB analysis. The aim of this study was to assess laboratory performance on reporting monoclonal gammopathy pattern during CSF OCB analysis based on external quality assessment surveys. Methods The CSF OCB surveys from the College of American Pathologists (CAP) from 2010 to 2015 were reviewed. The UK National External Quality Assessment Service (NEQAS) CSF OCB surveys from 2014 to 2017 were also reviewed. All monoclonal gammopathy patterns were confirmed by serum protein electrophoresis followed by immunofixation on a Sebia Hydrasys analyzer. Results There were 11 monoclonal gammopathy cases identified in the CAP OCB survey from 2010 to 2015. The average rate of CAP participants that correctly reported the pattern was 25.1% (range, 2.4%–66.7%). The most common pattern incorrectly reported was the systemic inflammation pattern, followed by the oligoclonal bands present/positive pattern. The NEQAS OCB survey from 2014 to 2017 had 4 monoclonal gammopathy cases and indicated a much higher number (average, 88.5%; range, 84.1%–90.8%) of participating laboratories to successfully detect monoclonal gammopathy. Conclusion Monoclonal gammopathy is still an underrecognized pattern in the CSF OCB analysis by the CAP participating laboratories and warrants further education.