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

CBC:

RBC: Decreased

WBC: Variable

PLT: Decreased

PBS:

Lymphoblasts

Normocytic

Normochromic

Anisocytosis, poikilocytosis, and nRBCs are usually not present.

BM:

≥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

Hyperuricemia

Hypercalcemia

Cytogenetics

Cytochemical Stains


References:

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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A Laboratory Guide to Clinical Hematology 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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