What is the FAB classification of acute lymphoblastic leukemia (ALL)?

Updated: Jul 03, 2019
  • Author: Karen Seiter, MD; Chief Editor: Koyamangalath Krishnan, MD, FRCP, FACP  more...
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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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