72 Acute Lymphoblastic Leukemia (ALL)

Michelle To and Valentin Villatoro

WHO Classification (2008):1

As of 2008, the WHO has classified ALL into categories based on the the lymphoblast origin and genetic abnormalities:

1. B Lymphoblastic Leukemia/Lymphoma

  • With recurrent genetic abnormalities
  • Not otherwise specified (NOS)

2. T Lymphoblastic Leukemia/Lymphoma


Affected Age: Primarily children 2-5 years old.2


Affected Cell:1

B and T lymphoblasts


ALL Blasts Cell Features:1,3,4

Size: Blasts are variable in size, usually smaller than myeloblasts


Nucleoli: Often indistinct, 0-2


Chromatin: Fine to coarse, dispersed chromatin


Cytoplasm: Usually scant and basophilic, vacuoles may also be present


Auer Rods: Not present


Auer Rods are thought to be fused primary granules and are only found in myeloblasts. Presence of auer rods is distinctive of AML and can be used to differentiate the condition from ALL if they are present.2


Laboratory Results for ALL:1,3,5


RBC: Decreased

WBC: Variable

PLT: Decreased





Anisocytosis, poikilocytosis, and nRBCs are usually not present.


≥20% Lymphoblasts

Hypercellular with replacement of normal hematopoietic tissue

Immunologic Markers:

B cell: TdT, CD10, CD19, CD22, CD24, CD34


T cell: TdT, CD1, CD2, CD3, CD4, CD5, CD7, CD8, CD10

Other Tests:

LD: Increased




Cytochemical Stains


1. Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al. editors. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues Volume 2. 4th ed. International Agency for Research on Cancer (IARC); 2008.

2. McKenzie SB. Introduction to hematopoietic neoplasms. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 424-45.

3. Leclair SJ, Bentley G.Precursor Lymphoid Neoplasms. 3rd ed. New Jersey: Pearson; 2015. p. 522-34.

4. Gatter K, Cruz F, Braziel R. Introduction to leukemia and the acute leukemias. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 331-370.

5. Roquiz W, Gandhi P, Kini AR. Acute leukemias. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 543-60.


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Acute Lymphoblastic Leukemia (ALL) Copyright © 2019 by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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