FAB CLASSIFICATION OF MYELODYSPLASIAS AND ACUTE MYELOID LEUKEMIA



The "FAB" (French, American, and British) classification of myelodysplasia and acute myeloid leukemia-Categories are morphologic, based on findings on bone marrow bx but do correlate roughly with prognosis.  LARGELY REPLACED BY WHO schema based largely on metaphase cytogenetics and fluorescent in situ hybridization (FISH).
  1. M0-Undifferentiated AML
    1. No Auer rods (rod-like, granular structures in cytoplasm pathognomonic for myelobasts
  1. M1-AML without maturation
    1. < 10% maturation beyond blasts
    2. Auer rods seen in 50%
  1. M2-AML with maturation
    1. > 10% maturation beyond blasts
    2. Auer rods seen in 70%
  1. M3-Acute promyelocytic leukemia
    1. Disseminated intravascular coagulation
    2. Auer rods seen in 100%
  1. M4-Acute myelomonocytic leukemia
    1. > 20% monocytes
    2. Increased lysozyme
  1. M5-Acute monocytic leukemia
    1. Gum infiltration
    2. High lysozyme level
    3. > 80% monocyts
  2. Erythroleukemia
    1. Nucleated RBCs
    2. Exclude B12 deficiency
  3. Megakaryoblastic leukemia
    1. Rapid myelofibrosis
    2. Resistant to treatment
(Sources include Core Content Review of Family Medicine, 2012AML )