Differential diagnostics

Differential diagnosis of M2 for acute non-lymphoblastic leukemia is performed with myeloblastic without maturation, myelomonoblastic and basophilic-cellular variants. In the M2 variant, in contrast to M1, the number of granulocyte maturation cells is more than 10%. In contrast to variant M4, when M2 there are no monoblasts containing nonspecific esterase. In basophilic cell leukemia, unlike myeloid blast, metachromasia is determined in blasts and peroxidase is absent, the serum of patients with elevated heparin and serotonin levels.

Of particular practical importance is the identification of promyelocytic leukemia among patients with acute non-lymphoblastic leukemia, since the treatment for this variant, including ATRA, is fundamentally different from the treatment regimens used for the remaining myeloid leukemia. The leading diagnostic feature of the M3 blasts is the characteristic dvulobolny form of the nuclei. However, the number of such cells in the blast population may be less than 25%, which significantly complicates the differential diagnosis of variants of MH and M2. Only a careful morphological analysis allows to identify characteristic cells. The lack of grit and Auer rods in the M3v variant makes leukemic promyelocytes similar to maturation monoblasts.

The differential diagnosis of M3v and M5b acute non-imphobular leukemia is based on the high activity of granulocyte enzymes in the first case and non-specific esterase in the second.

Diagnosing a rare variant of APL with t (11; 17) (PLZF / RARa), resistant to ATRA, with powerful cells similar to myeloblasts, presents great difficulties for morphologists. Practically, the diagnosis of this variant is based on data from a cytogenetic study. In the diagnosis of myelomonoblastic acute non-lymphoblastic leukemia, the definition of biclonal (most frequent) and biphenotypic variants is necessary. The visual difference between them is determined by carrying out successive reactions on a single smear of the bone marrow, first with ASD chloroacetate and then with α-naphthylacetate.

In the biclonal variant, 2 types of positive cells are detected: ASD-chloroacetate and α-naphthylacetate. In the bifenotypical variant, granules of both enzymes, colored in different (blue and red) colors, are found in all blasts. An increase in the number of atypical eosinophils suggests that the 16th chromosome is abnormal.

Differentiate M4 from options M2 and M5 according to cytochemical studies and the determination of the content of monocytoid cells.