According to some studies approximately 25% of B-cell lymphomas are
light chain negative. The percent of cases negative for light chains is
higher in the higher grade lymphomas with reports of up to 50% of B-cell
diffuse large cell lymphomas being light chain negative (Am J PAthol 1987,
128:181-201). Your problem may not be that you are missing light chain
expression but that they are negative. Are these cases positive by frozen
section or ipox? If so are they plasmacytic (remember, they don't have to
be waldenstroms or multiple myeloma to have cytoplasmic
immunoglobulin-plasmacytic differentiation can be seen in many tumors). If
you can show positivity for a B-cell antigen and negativity for surface
light chains you have an atypical B-cell population. You may need CD20 as
well as CD19 to detect this. Correlation with morphology is needed, of
course, for final diagnosis.
Maryalice
>
>I am interested in an opinion on the best way to detect Large-cell
>lymphoma(B Cell type) in lymph nodes.
>
>We currently disaggregate nodes then surface stain using
>45/19/kappa/lambda. Although
>we often have success ,there are cases where clearly the node is a
>malignant B-cell lymphoma by morphology in Surgical Pathology but we see
>no evidence in Flow. We have tried blocking with fetal calf and mouse
>serum. We have tried different gating strategies such as 45ss combined
>with 19ss gating or combined with fs. We have tried different staining
>combinations -19/5/kappa/lambda-45/19/10/kappa&45/19/10/lambda. We have
>tried live dead assays(7AAD) combined with surface staining in case a node
>was necrotic. Someone even suggested injecting nodes with PBS to express
>cells instead of mincing and grinding lymph nodes(they thought this might
>be a more gentle process).
>
>We don't seem to have the same problem with other malignant lymphomas in
>lymph nodes,just with the diagnosis of Large-cell lymphoma ( B-Cell type).
>Any suggestions would be greatly appreciated. Thanks for your help!
>
>Clinical Flow Lab
>Northwestern Memorial Hospital
Maryalice Stetler-Stevenson
Director Flow Cytometry Unit
Laboratory of Pathology, NCI, NIH
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