Masked monoclonal gammopathy in capillary electrophoresis.

BACKGROUND: Although the method of choice to detect M-protein is electrophoresis on an agarose gel, such gel electrophoresis (GE) is labor-intensive, time-consuming, and not standardized. In contrast to GE, capillary electrophoresis (CE) has some merits because it is automated, fast, and highly reproducible. However, CE results occasionally make the interpretation difficult and require additional confirmatory tests like GE.

METHODS: In order to assist a correct reporting of CE results and compatible interpretations between two different electrophoresis methods, we report here two unusual cases of monoclonal gammopathy by a pattern of polyclonal gammopathy upon CE interpretation in patients with end stage renal disease and multiple myeloma.

RESULTS: In these cases, serum CE showed the broad bumpy peak in the gamma region. This bumpy peak does not drop completely flat after the reaction with anti-FLC.

CONCLUSIONS: Because the plasma cell is a B-cell lineage and plays an important role in adaptive immunity, MG accompanying with PG is not rarely found in plasma cell dyscrasia. If the broad bumpy peak is observed in CE, careful examinations must be done to rule out the hidden M-peak. In our cases, a parallel use of gel-based methods was very helpful as it revealed monoclonal bands.