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CP Unknown

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CP Unknown

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  1. CP Unknown Heme-10/19/2011 KumaranMudaliar and Girish Venkataraman Loyola University Medical Center, Pathology

  2. What cells are these?- hematogones What cells are the purple population? -Plasma cells

  3. Additional plot of same case

  4. Explain the gates in this tube containing CD45, CD19, CD20, kappa and lambda Primary gate CD19/SSC Light chain negative cells colored green and forwarded to show on all plots.

  5. Hematogones • Hematogones: physiologic precursors of B-cells • 70 years ago, distinct ‘lymphoid appearing cells’ in the bone marrow (BM). • ‘Hematogones’ (hematogonia, meaning ‘blood-maker’) • 662 patients • 8% pts had 5% or more of hematogones • 24.6% < 16 YO had hematogones • 6.3% > 16 YO had hematogones • MC in patients: lymphoma, marrow regenerative states, immuno cytopenias, AIDS

  6. Problem • At 5% level, they are conspicuous on marrow smear and can be confused with neoplastic lymphoblasts

  7. Reference Ranges? • No accepted reference ranges • BM examination is not performed in healthy people

  8. 3 stages of Hematogone Maturation • Early • Usually comprise a small minority, but can become expanded in regenerating marrows • No expression of CD 20 /CD34+ • Intermediate • Majority in most marrows • -CD34-/CD20 dim/CD10+ • Late • In contrast to mature B cells, Cd34-/CD20+/maintain dim CD10 . Light chain surface+

  9. Stage 1 Hematogones CD34+/CD10+ Gated on all CD19+ cells Stage 2 hematogones Dimmer CD10, CD20 het Stg 2 (red) and stg 3 (blue) Hematogones lack CD34 Stage 3 hematogones -bright CD20, dim CD10 >90% of B-cells in this case are hematogones

  10. Immunophenotype • CD 10+ • CD 19+ • CD 20+ Variable expression • CD 38+ • CD 45+ • TdT + [subset] • CD 34 + [subset] • Kappa & Lambda -

  11. Differences between hematogones and lymphoblasts • Both present in CD 45 dim gate • Hematogones: low side scatter • Consistent, highly reproducible, maturational pattern • No aberrant or asynchronous antigen expression • B-ALL: relatively higher side scatter • Phenotypic abnormalities: • Myeloid Markers: 13, 33, 15 • T-cell: 2, 5, 7 • Concurrent expression: TdT and cytoplasmicIgM; 34 and 20 ; 34 and surface light chains • Loss of antigen expression on blasts: 45 – ; 10 – [B-ALL with MLL abnlties] ; 34 – [E2A-PBX1 fusion]

  12. Even tho both may express an antigen, difference in expression patterns and levels of specific antigens exist • IF TdT: hematogones (coarsely granular / speckled) to blasts (finely granular / even distribution) • Also, hematogones have higher #’s of TdT and CD 10 molecules / cell • Leads to brighter expression on FC • Hematogones have less CD 19 molecules/ cell • Hence dimmer expression on FC

  13. BM Core Biopsies • Hematogones: dispersed throughout marrow • Blasts: small clusters (> 5 cells)

  14. Issues • Differentiation can be challenging • Left Shifted Hematogones • Early stages after BM transplantation • Anti-CD20 immunotherapy • Majority of B-ALL lack CD20 expression . • -Phenotypic change

  15. Sources • McKenna RW, et al. Immunophenotypic analysis of hematogones (B-lymphocyte precursors) in 662 consecutive bone marrow specimens by 4-color flow cytometry. Blood. 2001 Oct 15;98(8):2498-507