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.
