We recently had a >3 cm solitary parotid mass from a 28 year old man. Histologically it seemed to be a reactive lymphoid hyperplasia. In flow there were small to large aganular CD45 bright cells consistent with lympocytes. The small to medium sized cells ( 70% ) were immunophenotypically unremarkable: 72% CD3 , 31% CD20, 16% kappa, 11% lambda. The large cells ( 30% ) were mostly ( 80%) B lymphoid, uniformly expressing CD19,20bright ,22. They were 58% positive for FMC7 and 26% positive for CD11c. The cells were negative for CD10,43,70 and 23. Monoconal CD19 / polyclonal anti light chain showed dim expression of 44% lambda : 20% kappa. Restaining with a second monoclonal kappa/lambda combination showed brighter fluorescence with a large lambda predominance. Subsequent immunoglobulin gene rearrangement studies showed no evidence of clonality.The tissue was negative for EBV by EBER and LMP. I guess this is just some anomalous staining with light chain reagents, but it bothers me that the staining of the small B cells looks perfectly good with both reagents, while the large cells show an excess of lambda with both PE and FITC labeled antibodies. I'd appeciate any and all opinions. Brent Dorsett Lenox Hill Hospital --- NYC
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