Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Normal

Immature B-cell (Later Hematogone)*


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› Microscopic Features:

• 2-4x larger than a mature RBC (variable size given their variable stage of maturation)
• High nuclear to cytoplasmic ratio
• Round Nucleus with immature chromatin (not clumped)
• Nucleoli are present (specially on less mature stages) but less prominent than blasts
• Cytoplasm is scant, light blue and lacks granules
• Usually it is morphologically indistinguishable from a Lymphoblast

› Normal % blood-PB, marrow-BM, lymphoid tissue-LN:

• PB: None
• BM: Scattered
• LN: None

› May Resemble:

• Myeloblast [Compare]
• Pronormoblast [Compare]
• Immature B-cell (hematogone) [Compare]
• Monoblast [Compare]
• Reactive lymphocyte [Compare]

› Differential Diagnoses:

If in blood or increased numbers in bone marrow: Maybe increased in newborns (not to be confused with acute leukemia) May be seen in recovering bone marrows (e.g. post-treatment) Acute Leukemia

› Classic Immunophenotype:

• CD19+
• CD10+
• CD20+/-
• CD34-
• TdT-

› Cartoon Image:


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› Misc:

• These are immature B-cells that are usually morphologically indistinguishable from lymphoblasts. Hematogones are a immunophenotypically diverse group of immature B-cells (Earlier forms have less mature markers such as CD34 and TdT while the more mature forms lack CD34 and TdT and partially express CD20) See the B-cell Maturation Diagram for more details