PMC6305046_01
Flow cytometry on the lymph node. (a) The majority of cells express bright CD45 with low side angle light scatter characteristic of lymphoid cells. (b) B-cells expressing CD20 range from small to large in size by forward light scatter. (c, d) The large neoplastic cells are positive for CD5 and negative for surface CD3. Cells showing the brightest intensity for CD3 and CD5 are background T-cells. (e, f) Large cells gated in red express dim CD5, but not surface CD3. The cells staining brightest for CD5 and gated in green are background T-cells and also stain for CD3. (g, h) Most CD20 moderate B-cells coexpressing CD5 gated in red also express CD10, while most CD20 dim B-cells gated in green do not express CD10. (i) Most of the CD20 moderate B-cells in red show moderate surface expression of kappa light chain. (j) Most of the CD20 dim B-cells in green do not show any surface light chain expression.
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fig1
Flow cytometric phenotyping identified the presence of two distinct, phenotypically abnormal B-cell populations (Figure 1).
(a) Hematoxylin and eosin stain 40x: the lighter staining nodular areas contain the larger cells of the blastoid variant mantle cell lymphoma (MCL). The darker staining areas near the center contain the small cells of the small lymphocytic lymphoma (SLL) component. (b) Hematoxylin and eosin stain 400x: the larger cells of the MCL are on the left and smaller cells of the SLL are on the right. (c) The MCL and SLL both stain for CD20. The SLL displays weaker staining. (d) The large nodules of the MCL stain weakly for CD3. The SLL is negative. (e) Both MCL and SLL stain for CD5. (f) Only the nodules of MCL stain for CD10. The SLL is negative. (g, h) The MCL stains for CyclinD1 (BCL-1) and SOX-11. The SLL component is negative. (i) The SLL in the center stains for CD23. (j) Many cells in the MCL nodules stain with Ki-67 indicating a high proliferation rate, whereas very few stain in the center SLL region stain indicating a low proliferation rate.
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fig2
Morphologic review of hematoxylin and eosin (H&E) stained fixed tissue sections and immunohistochemistry (IHC) confirmed the presence of two B-cell populations (Figure 2).
Flow cytometry on the bone marrow. (a) The following images come from the region gated as "lymphocytes". (b, c) The B-cells are small in size by forward light scatter and express moderate intensity CD19 and dim intensity CD20, a feature typical of chronic lymphocytic lymphoma/small lymphocytic lymphoma (CLL/SLL). This differs from the large size and intensity of these antigens in the mantle cell lymphoma of the lymph node. (d, e) The small B-cells stain for CD5 but are negative for CD3. The cells expressing bright CD3 are the T-cells. (f) A region color coded with orange represents the B-cells coexpressing CD5. (g, h) These cells do not express CD10 and the surface light chain expression is negative or equivocal.
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fig3
Flow cytometric phenotyping of the staging bone marrow aspirate detected small B-cells with features most often associated with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) (Figure 3).