Acute myeloblastic leukemia with maturation (M2 according to FAB classification) – diagnostics

• is 30-45% of all ONL;
• in the bone marrow more than 10% of neutrophilic cells at different stages of maturation and less than 20% of monocytes;
• blasts with extensive cytoplasm and, as a rule, with grit, sometimes with large granules of the type of Chediak-Higashi, with Auer sticks;
• blasts contain significant amounts of myeloperoxidase, lipids, ASD-chloroacetate esterase, as well as non-specific esterase and PAS-positive substance in diffuse form;
• blasts express myeloid antigens CD33, CD11, CD13, CD15, react with MCA to peroxidase and lysozyme, in cases with t (8; 21) coexpress lymphoid marker CD19, sometimes CD56 antigen;
• a dysplasia of cells of the neutrophilic series is determined: impaired segmentation of nuclei such as the pseudo-Selger anomaly; hypogranulation of cytoplasm, sometimes Auer’s sticks in mature forms;
• the number of eosinophils can be increased, there are no signs of dysplasia in them;
• translocation (8; 21) is detected in approximately 40% of cases. In accordance with the WHO classification, these observations are categorized into an independent category of acute non-lymphoblastic leukemia (ONLL) with recurring anomalies.

Acute basophilic cell leukemia (M2baz according to the FAB classification) – diagnosis

Acute basophilic cell leukemia (M2baz according to the FAB classification):
• is about 0, 5% of all acute non-lymphoblastic leukemia (ONLL);
• blasts of medium size, have oval or two-lobed nuclei;
• blasts contain coarse polymorphic granularity, positive with metachromatic coloration;
• blasts do not contain peroxidases, lipids and granulocyte esterase, stained with alcian blue;
• electron microscopic examination determines the structures characteristic of basophilic precursors and mast cells: electron-dense particles separated inside and crystalline material;
• translocation can be detected (6; 9) or 12p- deletion, in rare cases t (9; 22) (q34; qll).