HematologyOutlines

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

Immature B-cell (Early Hematogone)*

› Microscopic Features:

3-4x larger than a mature RBC
High nuclear to cytoplasmic ratio
Round Nucleus with immature chromatin (not clumped)
Prominent nucleoli
Cytoplasm is scant, light blue and lacks granules

› Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
PB: None
BM: 1%
LN: None
› May Resemble:
Myeloblast [Compare]
Pronormoblast [Compare]
Immature T-cell [Compare]
Monoblast [Compare]
Reactive lymphocyte [Compare]
› Differential Diagnoses:

If in blood or increased numbers in bone marrow:
B-Lymphoblastic leukemia (B-ALL)
CML's lymphoblastic Bast crisis (usually it's myeloblasts but can sometimes be lymphoblasts)

› Classic Immunophenotype:
CD19+
CD10+
CD20-
CD34+
TdT+
› Cartoon Image:

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for direct comparison
› Misc:
Very immature cells cannot be reliably distinguished from each other based on morphology alone. The exception are blasts with Auer Rod(s) which are unique to abnormal Myeloblasts and abnormal promyelocytes as noted in some AMLs and APL. 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