Lymphoblasts (e.g. Acute Lymphoblastic Leukemia: ALL)

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Blood/Blood Cells and Cellular Components ›› Lymphocytes ›› Abnormal

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›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: None
LN: None

›May Resemble:

›Differential Diagnoses:

If in blood or increased numbers in bone marrow or tissue:
B-Lymphoblastic leukemia (B-ALL)
T-Lymphoblastic leukemia (T-ALL)
CML lymphoblastic Bast crisis (usually it's Myeloblast s but can sometimes be lymphoblasts)

›Classic Immunophenotype:

B-lymphoblasts
CD19+
CD10+
CD20-
CD34+
TdT+
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T-lymphoblasts
CD3+
CD7+
CD34+
TdT+

›Cartoon Image:

Lymphoblasts (e.g. Acute Lymphoblastic Leukemia: ALL) cartoon

Click and drag Red blood cell for scale

for direct comparison

›Misc:

Blasts 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

Note: Abnormal lymphoblasts can show immunophenotypic abberancies (e.g. the gain of myeloid markers)