A Case of Mature B-cell Neoplasm with Light Chain Clonality Confirmed by Cytoplasmic Light Chain Expression Using Flow Cytometry

ABSTRACT

Surface immunoglobulin light-chain restriction is evidence of clonality in mature B-cell neoplasms. An aberrant pattern of surface light-chain expression can also be considered evidence of clonality. However, because this result could occur due to nonspecific staining or failure to stain, careful interpretation is required for accurate diagnosis. According to a previous study, flow cytometric analysis of the cytoplasmic pattern of light-chain expression in mature B-cell neoplasms is a viable approach to confirming clonality. Herein, we report a case, in which clonality could not be proven by surface light-chain analysis, but was demonstrated by cytoplasmic light-chain analysis. The case was in a patient with B-cell lymphoma showing non-specific surface expression of light-chains. This case support consideration of flow cytometric analysis of cytoplasmic light-chain expression patterns when aberrant surface light chain expression is observed, to confirm clonality of mature B-cell neoplasms.