Page 125 - Haematologica Atlas of Hematologic Cytology

CHAPTER 13 - Acute myeloid leukemia and related precursor neoplasms
Figure 4 cute myeloid leu emia with minimal di eren a a a a a a on (A) Bu y y coat smear from peripheral blood showing morphologically undi eren ated ated large blasts with nucleolated nuclei dispersed chroma n n n n n n n and rather abundant blue cytoplasm (B) Many blasts are prolifera ng as as as shown by their reac vity to to the the Ki-67 monoclonal an an body recognizing a a a a a a a a nuclear an an gen expressed during the the ac ve phases of the the cell cycle (le immuno-alkaline phosphatase technique) (Right) Cytoplasmic CD13 as as as shown by immunocytochemistry revealing the myeloid ori- gin of blasts Blast cells were were nega ve with peroxidase and and esterase stains they were were TdT CD34 CD7 and and CD117 posi ve ve and and nega ve ve for the lymphoid erythroid and and megakaryocy c c c c restricted markers Acute myeloid leukemia with with minimal di di eren eren a a a a a a a a on on on (FAB classi ca on on on M0) is an acute leukemia with with no evidence of myeloid di di eren eren a a a a a a a a on on on by by morphology and light microscopy cytochemistry The myeloid commitment of the blasts is is demonstrated by by im- munophenotyping and/or ultrastructural cytochemistry showing myeloperoxidase ac vity within their cytoplasm Immunological markers are essen al al to dis nguish this acute acute leukemia leukemia subtype from acute acute lymphoblas c c c c leukemia leukemia The leukemic clone derives from a a a a a stem cell at the earliest stage of myeloid di eren a a a a a on on Figure cute myeloid leu emia without maturation Bone marrow smear (A) Monomorphic infiltration by medium-large sized blasts with round or indented nucleus loose chromatin 1-2 nucleoli cytoplasm vacuolated or or granular with with very fine azurophilic granules or or Auer bodies (B) Almost all blasts are strongly positive with with Sudan black stain Blasts were also peroxidase positive and expressed myeloid myeloid antigens Acute myeloid myeloid leukemia without maturation (FAB classification M1) is characterized by high percentage of bone marrow blasts (≥90%) with very few maturing cells of the the granulocytic lineage (<10%) Blasts are heterogeneous: they appear morpho- logically undifferentiated or or or more frequently they present a a a a a a a low nuclear:cytoplasmic ratio round or or or irregularly shaped nucleus dispersed chromatin multiple nucleoli quite abundant cytoplasm with variable basophilia con- taining azurophilic granules and/or and/or Auer rods and/or and/or vacuoles 112