Acute Lymphoblastic Leukemia (ALL) Staging

Updated: Jun 03, 2021
Author: Karen Seiter, MD; Chief Editor: Matthew C Foster, MD 

Classification for Acute Lymphoblastic Leukemia

The World Health Organization (WHO)[1] and French-American-British (FAB)2  classifications for acute lymphoblastic leukemia (ALL) are provided below.

WHO classification of acute lymphoblastic leukemia

The WHO classifies ALL as B-lymphoblastic leukemia/lymphoma or T-lymphoblastic leukemia/lymphoma. The 2016 revision includes several provisional entities.

B lymphoblastic leukemia/lymphoma:

  • B-lymphoblastic leukemia/lymphoma, not otherwise specified (NOS)  
  • B-lymphoblastic leukemia/lymphoma with recurrent genetic abnormalities  
  • B-lymphoblastic leukemia/lymphoma with t(9;22)(q34.1;q11.2); BCR-ABL1
  • B-lymphoblastic leukemia/lymphoma with t(v;11q23.3); KMT2A rearranged  
  • B-lymphoblastic leukemia/lymphoma with t(12;21)(p13.2;q22.1); ETV6-RUNX1
  • B-lymphoblastic leukemia/lymphoma with hyperdiploidy  
  • B-lymphoblastic leukemia/lymphoma with hypodiploidy  
  • B-lymphoblastic leukemia/lymphoma with t(5;14)(q31.1;q32.3) IL3-IGH
  • B-lymphoblastic leukemia/lymphoma with t(1;19)(q23;p13.3); TCF3-PBX1
  • Provisional: B-lymphoblastic leukemia/lymphoma, BCR-ABL1–like  
  • Provisional: B-lymphoblastic leukemia/lymphoma with iAMP21

T lymphoblastic leukemia/lymphoma:

  • Provisional: Early T-cell precursor lymphoblastic leukemia
  • Provisional: Natural killer (NK) cell lymphoblastic leukemia/lymphoma

FAB classification of acute lymphoblastic leukemia (for historical purposes)

  • ALL-L1: Small cells with homogeneous nuclear chromatin, a regular nuclear shape, small or no nucleoli, scanty cytoplasm, and mild to moderate basophilia

  • ALL-L2: Large, heterogeneous cells with variable nuclear chromatin, an irregular nuclear shape, 1 or more nucleoli, a variable amount of cytoplasm, and variable basophilia

  • ALL-L3: Large, homogeneous cells with fine, stippled chromatin; regular nuclei; prominent nucleoli; and abundant, deeply basophilic cytoplasm. The most distinguishing feature is prominent cytoplasmic vacuolation


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