French-American-British (FAB) classification of AML
M1 (AML without maturation)
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Blasts>=90% of NEC; >=3% of blasts positive for peroxidase or SBB; Monocytic component <=10% of NEC; Granulocytic component <=10% of NEC |
M2 (AML with granulocytic maturation) |
Blasts 30-89% of NEC; Granulocytic component >10% of NEC; Monocytic component <20% of NEC |
M3 and M3 variant |
Characteristic morphology |
M4 (Acute myelomonocytic leukaemia) |
Blasts >=30% of NEC; Granulocytic component (including myeloblastc)>=20% of NEC AND EITHER BM monocytic component >=20% of NEC and PB monocyte count >=5x10e9/L OR BM monocytic component>=20% of NEC and lysozyme elevated* OR BM monocytic component >=20% of NEC and cytochemical confirmation of monocyte component in BM** OR BM resembling M2 but PB monocyte count >= 5x10e9/L and lysozyme elevated OR BM resembling M2 but PB monocyte count >= 5x10e9/L and cytochemical demonstration of monocytic component in BM |
M5 (acute monocytic monoblastic leukaemia) |
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M5a (without maturation or acute monoblastic leukaemia) |
Monocytic component >= 80% of NEC; Monoblasts >= 80% monocytic component |
M5b (with maturation or acute monocytic leukaemia) |
Monocytic component >= 80% of NEC; Monoblasts < 80% of monocyte component |
M6 (erythroleukaemia) |
Erythroblasts >= 50%; blasts >= 30% of NEC |
M7 (megakaryoblastic leukaemia) |
Blasts demonstrated to be megakaryoblasts, for example by ultrastructural cytochemistry showing the presence of platelet peroxidase or by immunological cell marker studies showing the presence of platelet antigens |
M0 (AML with minimal evidence of myeloid differentiation) |
Peroxidase and SBB positive in < 3% of blasts but blasts demonostrated to be myeloid by immunophenotyping |
BM - bone marow
NEC - non-erythroid cells
PB - peripheral blood
* Lysozyme in serum or urine elevated threefold compared with normal.
** Positive for NASA esterase activity, with activity being inhibited by fluoride.
This criteria given apply to the Bone marrow unless stated otherwise.
Reference:
Last updated on 25 February, 2000.
Prepared by HKMTAQAP Haematology & Serology Panel.
Copyright 2000 HKMTAQAP. All Rights Reserved.