Acute Leukaemias

CLASSIFICATION

French American British (FAB) Morphological classification Degree of maturation Lineage of the leukaemic blasts Histochemical stains Immunostains

AML M0Minimal Differentiation No evidence of myeloid differentiation by

morphology and light microscopy. Immunological markers are required. <5%. Any age but most common in infants and

older adults.

Medium sized blast cells with dispersed chromatin.

Round to indented nuclei. 1 or 2 nucleoli. Agranular cytoplasm <3% are SBB/MPO + CD34,CD33, HLA-DR +

AML M 1Without Maturation >90% blast cells without significant

evidence of maturation to more mature neutrophils.

5- 10% Any age usually adults SBB/MPO >3% Auer Rods

AML M2With Maturation >20% blasts with evidence of

maturation (>10% maturing cells of neutrophil lineage).

Auer Rods t(8;21) 10% Any age

AML M3Acute Promyelocytic Leukaemia Abnormal Promyelocyte predominate Hypergranular or Typical APL. Microgranular (hypogranular) Type. Young Adults, 5- 10% Auer Rods (Faggot cells) DIC t(15;17)

AML M4Acute Myelomonocytic Leukaemia Myelocytic and Monocytic differentiation. Myeloid maturation Older individuals 5- 10% Inv16 Monoblasts are nonspecific esterases + Myeloblast SBB +

AML M 5Acute Monocytic Leukaemia 80% or more of the leukaemic cells are

monocytic lineage ( monoblasts, promonocytes and monocytes)

10% Older age Organ involvement (CNS, Gum

hyperplasia, Skin) Nonspecific easterase +

AML M6Acute Erythroleukaemia Dyplastic erythroid precursors >50% erythroid precursors in the entire

nucleated cell population and >20% myeloblasts in the non-erythroid cell population.

<5% Therapy related SBB/MPO -

AML M7Acute Megakaryoblastic Leukaemia 20% blasts of which at least 50% are of

megakaryocyte lineage Uncommon Cytopenias often thrombocytopenia SBB – Immunostains Myelofibrosis