The likelihood of the emergence and development of resistance in acute myeloid leukemia is most often associated with increased expression of the multidrug resistance gene and, accordingly, beta-glycoprotein.

The prognosis in patients in whom a large amount of beta-glycoprotein is detected on the cells in the onset of the disease or an increased expression of the MDR1 gene is detected is significantly worse.

No clinical study is currently being conducted without an assessment of cytogenetic markers of leukemic cells. Depending on the long-term indicators in patients with various chromosomal abnormalities, three groups of “cytogenetic” prognosis were identified: favorable, moderate, poor. The criteria for assigning chromosomal abnormalities to a particular risk group vary from one clinical study to another.

These discrepancies relate to a number of aberrations, such as inv16, t (10; 11), 7q-, +8, which are often determined in patients with acute myeloid leukemia and a number of researchers are used as criteria for the differentiated treatment of acute myeloid leukemia.

As can be seen from the table, the number of research groups corresponds to the number of definitions given to groups of prognosis depending on the karyotype anomalies. This may be due both to differences in therapy (although it was very intensive in these studies) and to a small number of patients with each specific chromosomal aberration.

The long-term results in the respective forecast groups, despite the differences, largely coincide. This coincidence is explained by the fact that a small number of patients with a particular chromosomal aberration, analyzed in any prognosis group, cannot fundamentally affect the overall results of treatment.

It should be emphasized that the importance of cytogenetic markers in assessing the prognosis of the disease in a patient with acute myeloid leukemia is lost over time.

The universal prognostic factors in acute myeloid leukemia, as, however, in acute lymphoblastic leukemia and other tumors, is the treatment itself. Therapy should be adequate for doses of cytotoxic drugs, their combination, intervals and duration of treatment.

Inadequate chemotherapy is the only risk factor that is not associated with the biological characteristics of acute leukemia and patient status, and which, unfortunately, does not give chances for long-term survival to the majority of patients. It must be emphasized that the effects of inadequate therapy at the onset of the disease can never be corrected by further treatment, no matter how intense it is, because, as already discussed, the success of chemotherapy is determined by the intensity of the effect on the leukemic clone during the first stages of treatment.

The risk factors, which can also be called universal, include the patient’s age (especially over 60 years), the number of leukocytes in the onset of the disease (more than 30 • 109 / l), high levels of LDH in blood serum (more than 700 units), the period of previous myelodysplasia . Less common and not confirmed by all researchers are the signs by which the prognosis is assessed as follows: the presence of an infection before the start of chemotherapy, high serum creatinine or urine, severe hemorrhagic syndrome in the debut, neuroleukemia.

The morphological variant of acute myeloid leukemia is, of course, a fairly simple sign that allows an approximate assessment of the prognosis of a particular patient. Monoblastic, erythroblastic, megakaryoblastic, acute leukemias are quite unanimously classified as an unfavorable prognosis.

Standard induction chemotherapy is a classifying factor. After completing two courses of induction, patients are naturally divided into two groups: patients in complete remission and with a resistant form of acute myeloid leukemia. All patients with a resistant form of acute myeloid leukemia are in the group of poor prognosis.

The immunological phenotype of blast cells in myeloid leukemia is very diverse, and most often (in 80% of patients) aberrant expression of antigens is determined.

In other words, typical myeloid markers (CD11, CD13, CD14, CD15, CD33, CD36, CD41, CD42, CD65, HLA-DR; antigen of early CD34 precursor cells) can be expressed, first, together with antigens characteristic of lymphoid cells; secondly, their expression may be abnormal in the combination of early and late markers of cell differentiation; thirdly, over-expression of an antigen (for example, CD34) may be observed; fourth, there may be no expression of any antigen (for example, CD13 is expressed, but no CD33 is expressed). It is the aberrant immunophenotype that serves as a marker when monitoring minimal residual disease during remission.

In other cases, the detection of certain antigens on leukemic cells indicates only the aberrant immunophenotype and in some cases correlates with the prognosis.

For example, in acute myeloid leukemia, lymphoid markers occur in 14–60% of patients. According to German researchers, the CD2 antigen was expressed on blast cells in 57% of patients, CD5-y 60%, CD7-y 37%.

A study of the American group CALGB by definition of an immunophenotype in 339 patients with acute myeloid leukemia revealed the following frequency of lymphoid markers: CD2 (T-cell marker) was detected in 21% of cases (45 of 211 patients), CD19 (B-cell marker) – in 14 % (in 41 of 298 patients), CD2 and CD19, studied in combination, in 33% of cases (in 56 of 170 patients). Interestingly, with promyelocytic leukemia, a combination with lymphoid markers is noted 2 times more often, and with myelomonoblastic leukemia with eosinophilia (M4eo), 8 times more often than with other myeloid leukemias.

It is known that both M3 and M4eo are the most favorable variants of acute myeloid leukemia according to the effectiveness of treatment, therefore it is not surprising that in patients whose leukemic cells express, along with myeloid, lymphoid markers, the percentage of remissions was significantly higher (75 vs. 59%; р = 0.04) and overall survival over 2 years is better (43.8 ± 6.3% versus 29.8 ± 3.8%; p = 0.02). Detection of the early antigen of hematopoietic cells CD34 is also of prognostic significance: the prognosis in patients whose cells carry this marker is significantly worse than in those without it. It should be noted that this marker is most often determined in elderly patients with acute myeloid leukemia.

It is assumed that non-random acquired chromosomal aberrations exist in all patients with acute non-lymphoblastic leukemia (ONLL), but are determined using various methods in 70-80%. Detection of karyotype abnormalities allows us to predict the course of the disease and track the minimal residual population of leukemic cells.

Certain associations between cytogenetic and clinico-morphological features have been discussed previously. Fundamentally, at present, cytogenetic markers are becoming decisive in the choice of therapeutic approaches that were previously absolutely standard for all AML variants.

The most frequently detected cytogenetic abnormalities in acute myeloid leukemia include trisomy of chromosome 8, t (15; 17), t (8; 21), inv16, del 5q, 7q, monosomy of chromosome 5 and 7, translocation involving the region 11q23. As previously noted, leukemias with t (15; 17), t (8; 21), invl6 and 11q23 anomaly are classified in a modern category in a separate category. It should be emphasized that if the number of blast cells is less than 20%, but t (15; 17), inv16, t (8; 21) are detected, then the diagnosis of AML is nonetheless established.

Many cytogenetic aberrations, as a result of which one or another chimeric gene appears, can serve as a marker of a tumor clone in the period of clinical and hematological remission, i.e., used to monitor minimal residual disease. The table presents the most widely used in clinical practice molecular markers and the frequency of their occurrence in ONLL.

Unfortunately, when performing reverse transcriptase and direct polymerase chain reactions to determine the minimum residual population of leukemic cells, there are both false positive and false negative results.

The most common cause of false-positive results is not sufficiently accurate execution of the reaction, not in perfectly clean conditions, but false negative – in cases where transcription of mRNA is not detected in clonogenic leukemic cells with a certain chromosomal translocation.

The initial CNS lesion in acute myeloid leukemia is rare and is also most often associated with myelomonoblastic and monoblastic AML variants and during hyperleukocytosis.

In the debut of the disease in the blood are determined by very diverse changes. Power cells are found in 85-90% of patients, and their percentage ranges from 2-3 to 90-95. Neutropenia, anemia, and thrombocytopenia of varying severity are common at the time of diagnosis. In more than half of the patients, the number of leukocytes is increased, but the number of leukocytes more than 100 • 109 / l is determined in less than 20% of patients.

Hyperleukocytosis in acute myeloid leukemia, in contrast to ALL, often has clinical manifestations: leukostasis occurs in brain vessels, causing neurological symptoms (headache, workload, inability to concentrate), in vessels of the lungs, which manifests as respiratory failure, in kidney vessels, etc. e. As a prognostic criterion, the most frequently used leukocyte count is 30 • 109 / l; if at the time of diagnosis their content is more, patients are considered to be at high risk.

In certain forms of acute myeloid leukemia, most often in acute promyelocytic leukemia, a prominent clinical sign is DIC and activated fibrinolysis syndrome, which are manifested by severe bleeding or, less commonly, thrombotic complications. This is due to the release of procoagulants from azurophilic granules of leukemic cells and is often aggravated during cytostatic therapy due to their destruction.

In half of the patients with acute myeloid leukemia, hyperuricemia is observed, especially during the beginning of chemotherapy and tumor cell lysis. With monoblastic and myelomonoblastic acute leukemia, serum levels of lysozyme are possible. The increased content of lysozyme aggravates damage to the renal tubules, causes deep hypokalemia, not associated with diuretics and antibiotics. In a number of patients, an increase in the serum LDH content is noted. This indicator serves as a prognostic criterion: its 2-fold increase in relation to the norm indicates an unfavorable prognosis.

In the bone marrow is found from 20 to 99% of blast cells. The bone marrow is in most cases hypercellular, adipose tissue is completely replaced by tumor cells, the number of megakaryocytes is usually reduced, they are dystrophic. As noted, in 30% of patients with primary AML, one or other signs of hematopoiesis are noted. In this regard, it is unclear why in the modern classification of leukemias with this characteristic, belonging to different morphological and cytochemical variants, belong to a separate category.

Both dizeritroez, and / or dysgranulocytopoiesis, and / or dizegakaryocytopoiesis, or combinations thereof are detected. Dyserythropoiesis is characterized by hyperplasia of the red sprout or its substantial decrease, a disproportionate increase in the number of immature forms, megaloblastoidity, nuclear splitting, multi-core, vacuolization and cytoplasmic outgrowths, ring sideroblasts. Dizgranomonocytopoez is characterized by hyper- or hypoplasia of the cells of the man-made creatures, monitored by the pseudo-Egerger, the pseudopergerian anomaly, the dissociation between the degree of maturity of the nucleus and the cytoplasm, the hypersegmentation of the nucleus, the ring nuclei, microflora of the granulocyte, myelocyte, and the cell culture, the hypersegmentation of the nucleus, the ring nuclei, the microform of the granulocyte, the myelocyte, and the cell culture;

Dimegakaryocytopoiesis includes the following features: hyper- or hypoplasia of the germ, an increase in the number of microforms, single-binuclear megakaryocytes, vacuolization of the cytoplasm.

Trilinear dysplasia occurs on average in 5–7% of patients (with age, the probability of detecting this morphological phenomenon increases by 2–3 times). It was believed that patients in whom, at the time of diagnosis of OL, three-linear hemopoiesis dysplasia is determined, regardless of the ONLL variant, should be included in the group of poor prognosis for long-term survival. However, as emphasized, modern works refute this position.

The diagnostic signs and features of acute myeloid leukemia considered are the result of routine research. No less significant at present for the differential diagnosis and assessment of prognostic factors are those signs that are established during immunophenotyping of power cells, with their cytogenetic and molecular-biological studies.
Source: MedUniver

The term “acute myeloid leukemias” (AML) unites a group of acute leukemias arising from the precursor cell of myelopoiesis and differing in certain morphological, immunophenotypic and cytogenetic characteristics. About 10% of AML have an erythroid or megakaryocytic orientation, therefore the term “acute non-lymphoblastic leukemia” (ONLL) is also considered eligible. Thus, AML, or ONLL, is a group of dissimilar leukemias that require different therapeutic approaches.

Acute myeloid leukemia (AML) is diagnosed at any age, but the frequency of its occurrence increases in older age groups. The median age at which AML is diagnosed is 60–65 years, that is, it is a disease of the elderly. On average, AML affects 2 people per 100,000 population per year.

Unlike ALL, myeloid leukemia may be preceded by a pre-leukemic phase (pre-leukemia, myelodysplastic syndrome). Almost 30-40% of elderly patients with the so-called primary (de novo) ONLL detected myelodysplasia.

For acute myeloid leukemias, the connection with radiation, chemical factors (benzene), alkylating agents (mustargen), and epipodophyllotoxins (etoposide) has been proven more clearly than for ALL. The incidence of AML increases when interacting with substances such as totratrast (radiographic contrast agent), pesticides, dyes, rubber, etc.

The clinical manifestations of the disease are very non-specific. Weakness and malaise may precede the diagnosis many months before it is established. Pallor, dizziness can be manifestations of anemic syndrome. Fever and sweating in the debut of the disease are observed in 15-20% of patients, and they may not be associated with any infectious process, which is also often determined at the onset of the disease (tonsillitis, pneumonia, etc.). Frequent symptoms are those or other manifestations of hemorrhagic syndrome.

Petechial rash, ecchymosis is detected at the time of diagnosis in 50% of patients. Sometimes the only symptom of the disease can be bleeding: uterine or nasal, from the gastrointestinal tract, gums, kidneys, etc.

About half of patients complain of a slight weight loss. Ossalgia is noted in 20% of patients. Organomegaly is not a bright diagnostic sign of AML, but an increase in the size of the liver, spleen, lymph nodes is found in 50% of patients. In 10% of patients, specific skin infiltration is defined – leukemides, and most often in acute myeloblastic and monoblastic leukemias. For these same options, a characteristic feature is gum infiltration.

Diagnosis of acute leukemia is based on the assessment of morphological features of bone marrow cells and peripheral blood. The diagnosis is established only when so-called blast cells in the bone marrow or peripheral blood are characterized by a delicate net structure of nuclear chromatin. The number of blast cells in this case should be 20% or more.

If it is less in the bone marrow, but its content in the blood is 20% or more, then the diagnosis of acute leukemia is also established. Determining the belonging of tumor cells to the myeloid or lymphoid hematopoietic lines when using the usual Romanovsky – Giemsa staining is possible only in 70% of cases. For a more precise definition, other diagnostic approaches are needed: immunophenotyping, cytochemical, cytogenetic, molecular biological and cultural studies.

A new WHO classification can be called a list of diseases characterized by a specific set of features, since it lacks a single classification feature that existed, for example, in developing the FAB classification (morphology and cytochemistry of blast cells). As a result, some forms of OL can simultaneously be assigned to different categories.

Thus, acute leukemias with Hq23 translocations are assigned to the first classification category, but the 11q23 segment anomaly is often detected in patients with secondary acute leukemia. At the same time, secondary acute myeloblastic leukemias are separated into a separate category, so it is not clear how to classify AML, which arose after previous chemotherapy of a tumor and is characterized by anomalies of the 11q23 segment, as a disease of the first category or the third.

There is also a question regarding other consistently detectable chromosomal aberrations: for example, why in the first classification category such anomalies as t (6; 9) and anomalies of chromosome 3 that have clear morphological and clinical characteristics are not considered.

In those situations when it is not possible to analyze the karyotype of blast cells, the only principle by which acute leukemia, morphological, will be classified. Again, it is unclear to which classification category AML is classified, which, for example, according to the FAB classification, is characterized as myelomonoblastic, but arose after prior chemotherapy and in which signs of myelodysplasia are determined in the bone marrow.

The presence of myelodysplasia is the basis for the selection of the second classification category. As noted earlier, morphological signs of dysplasia are detected in patients with different types of AML (myeloblastic, myelomonous and monoblastic, erythroblastic, rarely promyelocytic, etc.), with AML developed from MDS, secondary AML. This pattern was previously noted by other international experts, so it is not quite clear why a special category was selected.

Previously, it was believed that the presence of signs of myelodysplasia determines an unfavorable prognosis, and therefore, it seems that leukemias with these symptoms were considered as a separate category. However, it has now been established that the symptoms of myelodysplasia in the debut of the disease are observed quite often and do not affect the results of therapy.

In the new WHO classification, acute lymphoblastic leukemia is considered in the section of tumors arising from the precursor cells of T and B lymphocytes. In the section of lymphatic tumors from the early progenitor cells are presented:
1) lymphoblastic leukemia / lymphoma from B-lymphocyte progenitor cells (synonym: acute lymphoblastic leukemia from B-cell precursors);
2) lymphoblastic leukemia / lymphoma from T-lymphocyte progenitor cells (synonym: acute lymphoblastic leukemia from T-lymphocyte progenitor cells).

Perhaps the equivalent use of the presented definitions, the authors of the classification only believe that when the content of blast cells in the bone marrow is 25% and it is more expedient to speak of acute leukemia, less than 25% of lymphoblastic lymphoma. However, most often these terminological difficulties are speculative, since the therapy is the same in either case.

In accordance with the FAB classification, the described forms of acute lymphoblastic leukemia were defined as variants L1 and L2, however, at present, these names are practically not used. According to the FAB classification, the third form of ALL, in the modern classification, is assigned to a large section of tumors from mature (determined by immunophenotype) B-cells as Berkitt-like leukemia / lymphoma. Unfortunately, the new classification does not give clear immunophenotypic characteristics of specific sub-variants of B-and T-cell lymphoblastic leukemias, which often causes difficulties in interpreting the results of flow fluorocytometry.

Differential diagnosis of acute lymphoblastic leukemia

The differential diagnosis of acute lymphoblastic leukemia and non-Hodgkin’s lymphomas (NHL) in the blast-type leukemization stage necessitates a detailed immunological study. Those hemoblastosis in which the blasts have the phenotype of early progenitors are designated as ALL / NHL, and the rest – as NHL from peripheral cells. So, when expressing antigens of early B-precursors (CD19, CD20, CD22), TdT enzyme and in the absence of membrane immunoglobulin, B-ALL / NHL is diagnosed, and in the presence of T-precursor phenotype – T-ALL / NHL.

Similar difficulties are encountered in the differential diagnosis of acute non-lymphoblastic leukemia (ONL) and myeloid sarcomas. Currently, myeloid sarcomas in the WHO classification are considered in the section of acute leukemia and can be presented as the first manifestation of the disease with rapid leukemization by the type of acute non-lymphoblastic leukemia (ONLL).

The cellular composition of myelosarcoma can be represented by blasts of various types or by maturing elements of the granulocyte series. Morphocytochemical and immunophenotypic characteristics of blasts, cytogenetic abnormalities are identical to those observed in acute non-lymphoblastic leukemia (ONLL).

In patients with multiple myeloma, plasma cell leukemia may occur. It usually manifests itself as a terminal phase of myeloma, although there are descriptions of cases when it is regarded as an independent disease. The leukemic population in the blood and bone marrow is represented by plasmablasts, as well as protoplasmocytes and plasma cells. All elements of the plasma line are morphocytochemically and immunophenotypically characterized as B cells with clonal expression of immunoglobulins.

Diagnosis of hemoblastosis

Diagnosis of hemoblastosis can be difficult with scanty punctate bone marrow. This can be observed in aplastic conditions, myelofibrosis, MDS with fibrosis or tumor metastases. In cases where a proliferative pathological clone has been identified (myeloblasts, megakaryoblasts), acute leukemia with myelofibrosis is diagnosed, otherwise acute or chronic idiopathic myelofibrosis is diagnosed. In acute panmielosis, in contrast to chronic idiopathic myelofibrosis, young forms of myelopoiesis, including mononuclear megakaryocytes, predominate in the bone marrow.

Acute leukemias also have to be differentiated from blast crises in the inventories and, in particular, CML. Special difficulties are presented when the CML manifests with a blast crisis. The presence of the Ph-chromosome in most cases helps to establish the diagnosis of CML. It should be noted that the Philadelphia chromosome is also detected in rare cases of myeloblastic and in 25% lymphoblastic leukemia, which makes diagnosis difficult. Imperious crises of CML can be myeloid and lymphoid, and differential diagnosis is carried out with the appropriate variant of acute leukemia. The picture of the bone marrow in the myeloid blast crisis of CML is much more variegated than in ONLL: eosinophils, basophils may be present in the granulocyte sprout, pathological microforms of megakaryocytes are found.

Cells in the blast population are more diverse in their morphoimmunological features compared with acute leukemia, myeloblasts, erythroblasts, megakaryoblasts can be detected at the same time, and lymphoblasts in some cases. The picture of lymphoid blast crisis is more monomorphic and similar to that in ALL. Ph-positive clone in CML and ALL is different in its functional features, which is associated with the structural features of BCR / ABL oncogenes in these two hemoblastosis. In ALL, the BCR / ABL gene encodes the abnormal p190 protein, and in CML, the p210 protein is produced. With the help of molecular research methods (PCR reaction) establish an accurate diagnosis.

Certain diagnostic difficulties may also occur in the differential diagnosis of ONLL and metastases of alveolar rhabdomyosarcoma and neuroblastoma in children.

Acute non-lymphoblastic leukemia differentiate

M5a acute nonlymphoblastic leukemia is differentiated from leukemias of the M0, Ml and M7 variants, as well as from acute lymphocytic leukemia. In these cases, the leading criteria are cytochemical and immunophenotypic parameters. A specific feature of monoblasts M5a and M5b is α-naphthyl acetate esterase, which is inhibited by sodium fluoride. Acute monoblastic leukemia with maturity is also differentiated from atypical promyelocytic leukemia without grain. Characteristic cytochemical markers (non-specific esterase and peroxidase) make it easy to distinguish them.

In the differential diagnosis of M6 and other variants of acute non-lymphoblastic leukemia, it is necessary to take into account the possibility of two subvariants of the disease: with the presence of an extended pathological red sprout (erythromyelosis) and with total bone marrow metaplasia with leukemic erythroblasts (erythroid leukemia).

In the first case, differentiated from RAIB MDS. If the number of erythroid progenitors is more than 50%, then the number of blasts should be recalculated to the non-erythroid fraction. In the event that the number of blasts exceeds 20%, M6 is diagnosed with acute non-lymphoblastic leukemia, in the opposite – RIBS MDS. If dysplasia is expressed in more than 50% of myelopoiesis cells, then, at the suggestion of the WHO classification, a variant of acute non-lymphoblastic leukemia with multilinear dysplasia is diagnosed.

In erythroleukemia, differential diagnosis is carried out with megakaryoblastic and lymphoblastic leukemias. The presence of erythroid erythroblasts (NAE3, NAE9, glycophorin A) and the absence of megakaryocytic and lymphoid antigens are taken into account.

Megakaryoblastic leukemia is distinguished from M0 and M6 in acute non-lymphoblastic leukemia based on the expression of specific antigens (CD41 and CD61). It should be noted that leukemic megakaryoblasts sometimes differ in some morphocytochemical features, which indirectly can suggest the need for advanced immunophenotypic studies. Thus, the irregular shape of the cells, the presence of outgrowths of the cytoplasm, its pronounced basophilia, the presence of megakaryocytes in the blood and their nuclei suggest a megakaryoblastic variant of acute non-lymphoblastic leukemia.

In addition, megacaryoblastic leukemia is differentiated from acute panmielosis with myelofibrosis. The presence of more than 50% of blasts expressing specific antigens, and the absence of trilinear myeloid cell dysplasia, make it possible to diagnose acute megakaryoblastic leukemia, even with fibrosis.