Laboratory diagnosis of acute leukemia – analyzes

A blood test for acute leukemia. Most patients with acute leukemia (OL) at the time of diagnosis of the disease have normochromic normocytic anemia, which is more pronounced in acute myeloblastic leukemia. With the development of hemorrhagic complications, hypochromia may occur due to iron deficiency. The number of peripheral blood leukocytes varies widely (from 1 • 109 / l to 200 • 109 / l), but more often it remains at the subleukemic level and does not exceed 20-30 • 109 / l.

The most pronounced leukocytosis is observed in patients with T-ALL and acute monoblastic leukemia. When calculating the leukocyte formula in 90% of patients with acute leukemia blast cells are detected, the number of which can vary from 1-2 to 100%. In typical cases, there are no intermediate forms of neutrophilic cells between the blasts and mature granulocytes (“leukemic failure”, or hiatus leukaemicus).

In 20% of patients, the number of blast cells exceeds 50 × 109 / l, and in 10% of the blasts in the peripheral blood are absent (pancytopenia and relative lymphocytosis are usually noted). At the level of leukocytes above 100 • 109 / l, the risk of the development of leukostatic complications (neurological disorders, acute respiratory distress syndrome, in men, in addition, priapism) sharply increases.

Thrombocytopenia is detected in the overwhelming number of patients with acute leukemia and is more pronounced in acute myeloblastic leukemia (AML) (in half of the patients the number of platelets is less than 50 • 109 / l). At the same time, in 1–2% of patients thrombocytosis is noted (more than 400 • 109 / l).

In some patients, an increase in prothrombin and partial thromboplastin time may be noted; in acute promyelocytic leukemia, a decrease in fibrinogen level and other signs of DIC are often observed. It should be noted that the development of the syndrome of DIC is possible with any variant of acute leukemia.

Myelogram with acute leukemia. The study of bone marrow aspirate is needed to diagnose and establish a variant of acute leukemia. The number of myelokaryocytes is usually increased, megakaryocytes are absent or their number is reduced. When calculating the myelogram, at least 20% of blasts are detected, constriction of normal hemopoiesis sprouts. To verify the variant of acute leukemia, it is necessary to conduct cytochemical, immunological and cytogenetic studies, the results of which have prognostic significance and allow planning medical tactics.

Infectious complications

Infectious complications (respiratory infections, bacterial sepsis) rarely develop in the onset of the disease, but have important practical and prognostic significance. Complications of various etiologies (bacterial, viral, fungal) usually occur during treatment, most often with the development of agranulocytosis and are one of the main causes of deaths.

Neuroleukemia in most cases manifests with a meningeal symptom complex or a picture of an intracerebral tumor (nausea, vomiting, headache), isolated lesion of cranial nerves is much less common (nn oculomotorius, facialis).

Clinical signs do not allow to reliably differentiate acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL) without performing cytochemical and immunological studies of blast cells. However, some symptoms are more likely to occur in certain types of acute leukemia (OL).

Acute myeloid leukemias are characterized by more vivid symptoms: patients usually have intoxication, anemic, and hemorrhagic syndromes, often with severe infectious complications. 90% of patients with ALI develop syndrome of DIC. Acute monocytic, rarely myelomonocytic leukemia more often than other variants of AML are accompanied by hypertrophic gingivitis, lymphadenopathy, the appearance of leukemides on the skin and high leukocytosis.

In acute erythromyelosis, the anemic syndrome, macrocytosis and peripheral blood normocytosis are leading. Acute megakaryoblastic leukemia is usually characterized by pronounced myelofibrosis, which makes it difficult to obtain bone marrow aspirate and serves as a basis for performing bone marrow trephine biopsy to verify the diagnosis.

Acute lymphoblastic leukemias are characterized by more scarce clinical manifestations: intoxication, anemic and hemorrhagic syndromes are less pronounced, and infectious complications occur less frequently. At the same time, in patients with acute lymphoblastic leukemia (ALL), ossalgia, lymphadenopathy (including an increase in mediastinum), hepatosplenomegaly and neuroleukemia are significantly more common.

Debut of acute leukemia

The debut of acute leukemia has no characteristic clinical manifestations.
For children and young people, a more acute onset is more typical, in which patients are worried about progressive general weakness, malaise, headache, shortness of breath, myalgia, ossalgia, less often – abdominal pain, fever. In mature and advanced age, the disease usually develops more slowly and is characterized by a predominance of symptoms of anemia and intoxication.

More rarely, the first manifestation of acute leukemia (OL) are hemorrhages in the skin, nose bleeds, blood admixture during defecation, mucosal bleeding, hypertrophic gingivitis, and necrotic stomatitis. Finally, in 5% of patients, a diagnosis is made by examining peripheral blood for other diseases.

On examination, most patients determine the paleness of the skin and mucous membranes due to anemia, and manifestations of hemorrhagic syndrome (petechiae and / or ecchymosis on the mucous membranes of the oral cavity and on the skin, signs of internal bleeding are possible). Rarely marked increase in the liver and spleen, lymphadenopathy.

With the developed clinical picture of acute leukemia (OL), the following syndromes are expressed to varying degrees:

1) syndrome of tumor intoxication (weakness, fatigue, weight loss, increase in body temperature, not associated with infection);
2) anemic syndrome (shortness of breath during normal exercise, dizziness, pallor of the skin and mucous membranes);
3) hemorrhagic syndrome (hemorrhage, bleeding mucous membranes, in severe cases – profuse bleeding of various localization, bleeding in the brain);
4) syndrome of leukemic proliferation (ossalgia, swollen lymph nodes, liver, spleen, hypertrophic gingivitis, neuroleukemia);
5) syndrome of infectious complications (local or generalized infections).

Basic data of clinical, laboratory and instrumental studies

In most patients, the symptoms of acute leukemia are not specific, however, the diagnosis is usually not difficult to study the history of the disease, physical data, the study of peripheral blood and myelogram.

I. Symptoms of acute leukemia: Weakness, indisposition, shortness of breath; hemorrhagic manifestations from minimal effects and injuries; weight loss; ossalgia; abdominal pain (rare); neurological symptoms (rare).

Ii. Clinical signs of acute leukemia: Anemic syndrome (weakness, pallor, tachycardia); hemorrhagic syndrome (ecchymosis, petechiae, internal and external bleeding); fever and infections (pneumonia, sepsis, pararectal abscess); lymphadenopathy, hepatosplenomegaly, expansion of the mediastinum; infiltration of the gums and skin (rarely); increased kidney and development of renal failure (rare); damage to the meninges and cranial nerves (rare).

III. Important laboratory and diagnostic tests for acute leukemia. A blood test with leukocyte count; coagulogram with determination of fibrinogen level; biochemical parameters (transaminases, creatinine, uric acid, calcium, phosphorus, electrolytes); a study of aspirate and trepanobioptata (not in all cases) of the bone marrow; determination of the blast cell phenotype, cytogenetic (according to indications – molecular genetic) studies; analysis of cerebrospinal fluid; X-ray of the chest, ultrasound of the abdominal cavity, computed tomography of the chest and abdominal cavity (according to indications in acute lymphoblastic leukemia); HLA-typing (in young patients).