Dual kappa and lambda expressing in mature B-cell neoplasm: An unusual case

A 57 years old male presented with transfusion dependent anemia for last 2 months with mild weight loss and on and off fever. On examination he was found to have small axillary lymph nodes with moderate splenomegaly. Flow cytometry revealed 63.2% cells in the lymphocyte window in cluster of differentiation (CD) 45 versus side scatter plot. Further analysis on CD-19 gated cells showed that - 75.9% of these cells expressed CD-19 plus the expression of CD23, CD25, CD43, CD20 and CD22. The entire cluster showed dual expression of kappa and lambda light chains. Final diagnosis of low-grade B non-Hodgkin lymphoma was made. Given that dual kappa and lambda expressing in mature B cell neoplasm has been described in literature, it is important to differentiate such cases from reactive lymphoid proliferations.