Classification of acute leukemia

In order for a practical physician to be guided by the new classification of acute leukemias , proposed by WHO, we present the old FAB classification, which provided for the allocation of the following forms of ONL.

■ M0 - acute myeloblastic leukemia with minimal myeloid differentiation. With this form of leukemia blasts without granularity account for more than 30% of myelokaryocytes. Less than 3% of blasts contain lipids or myeloperoxidase. Blasts belong to the myeloblasts according to the results of phenotyping( CD13 +, CD33 +).

■ M1 - acute myeloblastic leukemia without maturation. Blasts without granularity or with single azurophilic granules, may contain Aueer's bodies;single nucleoli. Blasts should be 90% or more of the non-erythropoietic cells. More than 3% of blasts are peroxidase-positive and contain lipids.

■ M2 - acute myeloblastic leukemia with maturation. Blasts morphologically and cytochemically do not differ from M1, constitute from 30 to 89% of non-erythropoietic cells. The wands of Auer, as a rule, are single, ordinary. Myelocytes, metamyelocytes and granulocytes can be detected in a variable amount( more than 10%) and often have abnormal morphology. Monocyte cells account for less than 20% of non-erythropoietic cells.

■ M3 - acute promyelocytic leukemia. Most of the cells correspond to neoplastic promyelocytes. The cells are often destroyed, so that you can identify freely located granules and Aueur sticks. Blast nuclei are located eccentrically, vary in shape and size, often consist of two parts.

■ M4 - acute myelomonoblastic leukemia. The total number of blasts in the bone marrow is more than 30%, with more than 20% of blasts of the bone marrow and / or more than 5x109 / l of peripheral blood cells - monoblasts, promontocytes or monocytes. The diagnosis of M4 is made when the changes in the bone marrow correspond to M2, but in the peripheral blood, more than 5.0x109 / l monocytic cells are detected. Promonocytes and monocytes differ by a distinct diffuse response to the presence of a-naphthylacetate esterase inhibited by NaF.A characteristic feature of M4 is an increase in the concentration of lysozyme in the blood and urine by more than 3 times.

■ M5 - acute monoblast leukemia. Blasts account for more than 30% of myelokaryocytes. In the bone marrow of 80% or more of the non -erythroid cells are monoblasts, promonocytes and monocytes. M5 type blas-tov divide into two forms: M5a - monoblast make up 80% or more of all blasts;M5b - monoblasts are less than 80%, and the rest - promonocytes and monocytes, the latter accounting for an average of 20% of blasts.

■ MB - acute erythromyelosis. In the red bone marrow, erythrocarytes account for more than 50% of all cells, are characterized by lobulation and fragmentation of the nucleus, multinucleation, giant forms. Blasts make up more than 30% of non-erythroid cells and can refer to any of the FAB variants of blasts other than M3.Such erythroblasts often go into the peripheral blood. Erythrocaryocytes are characterized by a diffuse-granular reaction to a-naphthylacetate esterase.

■ M7 - acute megakaryoblastic leukemia( introduced in the FAB classification in 1985).More than 30% of the cells are immature, very polymorphic blasts. Often strongly basophilic cytoplasm of blasts forms pseudopodia. Routine cytochemistry is not indicative. Often reveal myelofibrosis.

In Table.the main classifications of acute leukemia are given.

Acute Leukemia Classification Table

Classification Table for Acute Leukemia

Continuation of Table.

Continuation of Table.