Acute non-lymphoblastic leukemia with recurring cytogenetic abnormalities
Characteristic cytogenetic abnormalities in acute non-lymphoblastic leukemia (ONLL) are usually represented by balanced translocations. Such recurring, or non-random, cytogenetic anomalies include t (8; 21), t (15; 17), t (l6; 16), inv (16) and an anomaly llq23, resulting from the translocation of chromosome 11 with various partners (about 20) . For most of these leukemias, a high frequency of complete remissions and a more favorable prognosis are typical. Some morphological features are characteristic of them.
Acute myeloid leukemia with t (8; 21) (q22; q22); (AML1 / ETO). This anomaly is detected in 5-12% of cases of acute non-lymphoblastic leukemia (ONLL), more often in young patients, occurs predominantly with myeloblastic leukemia with maturation (M2 according to FAB classification), sometimes with myeloblastic leukemia without maturation (Ml) or myelomonoblastic (M4).
Blasts express both myeloid (CD13, CD33), and often the lymphoid antigen CD 19. CD34 and CD56 are less commonly defined. For elements of the neutrophilic series, marked dysplasia, the presence of pelgheroid forms, homogeneous pink staining of the cytoplasm are characteristic. In mature neutrophils, in some cases Auer rods can be detected. The number of eosinophils may be increased, but there is no dysplasia in them. The presence of t (8; 21) gives a basis, when the number of blasts is less than 20%, to diagnose ONLL, and not MDS.
In ONLT with t (8; 21), the prognosis is good, with a high frequency of complete remissions and a long duration of survival with adequate treatment. Expression of the CD56 antigen worsens the prognosis.
Acute myeloid leukemia with inv (16) (pl3; q22) or t (16; 16) (pl3; q22); (CBFb / MYH11). In this case, leukemia (M4eo according to the FAB classification) in the bone marrow myeloblasts, monoblasts and anomalous eosinophil component are determined. Immunophenotyping on blasts reveals common myeloid antigens (CD13, CD33, MPO) and markers of monocytic differentiation (CD14, CD11b, CD11c, CD64, CD36, and also lysozyme). Promyelocytes and myelocytes of the eosinophilic series are distinguished by the presence of pathological granularity.