CP Unknown Heme-10/19/2011 Kumaran Mudaliar and Girish Venkataraman Loyola University Medical Center, Pathology
Mar 31, 2015
CP Unknown
Heme-10/19/2011Kumaran Mudaliar and Girish VenkataramanLoyola University Medical Center, Pathology
What cells are the purple population?-Plasma cells
What cells are these?- hematogones
Additional plot of same case
Explain the gates in this tube containing CD45, CD19, CD20, kappa and lambda
Primary gate CD19/SSCLight chain negative cells colored greenand forwarded to show on all plots.
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
Problem
• At 5% level, they are conspicuous on marrow smear and can be confused with neoplastic lymphoblasts
Reference Ranges?
• No accepted reference ranges – BM examination is not performed in healthy people
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+
Gated on all CD19+ cells
Stage 1HematogonesCD34+/CD10+
Stage 2 hematogonesDimmer CD10, CD20 het
Stage 3 hematogones-bright CD20, dim CD10
>90% of B-cells in this case are hematogones
Stg 2 (red) and stg 3 (blue)Hematogones lack CD34
Immunophenotype
• CD 10+ • CD 19+ • CD 20+ Variable expression• CD 38+ • CD 45+• TdT + [subset]• CD 34 + [subset]• Kappa & Lambda -
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 cytoplasmic IgM; 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]
• 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
BM Core Biopsies
• Hematogones: dispersed throughout marrow• Blasts: small clusters (> 5 cells)
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
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