What Is Acute Myeloid Leukemia and How Is It Classified?

What Is Acute Myeloid Leukemia and How Is It Classified?

Discuss in briefly acute myeloid leukemias.
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Acute myeloid leukemia is a heterogeneous disease characterized by the infiltration of malignant myeloid cells in the blood, bone marrow, and other tissues.

“Understanding the role of acute myeloid leukemia in blood cancers”

“Importance of studying acute myeloid leukemia for better healthcare outcomes”

Acute myeloid leukemia Classification

Revised FAB (French American British) Classification for Acute myeloid leukemia

“Common challenges in diagnosing and managing acute myeloid leukemia”

Acute myeloid leukemia Clinical Features

• Due to bone marrow failure
  • Anemia produces pallor, lethargy, and dyspnea.
  • Bleeding manifestations due to thrombocytopenia cause petechiae and bleeding from the gums.
  • Infections of the mouth, throat, skin, respiratory, and other sites are common.
  • Fever is attributed to infections in acute leukemias.

“Steps to explain what acute myeloid leukemia is”

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• Due to organ infiltration
  • Pain and tenderness in bones.
  • Presence of gum hypertrophy
  • Lymphadenopathy and enlargement of tonsils may occur.
  • Moderate splenomegaly, splenic infarction, subcapsular hemorrhages
  • Presence of hepatomegaly
  • Leukemic infiltration of the kidney
  • Chloroma and granulocytic sarcoma is a localized tumor-forming masses occurring on the skin or orbit.
  • Meningeal involvement manifested by raised intracranial pressure, headache, nausea and vomiting, blurring of vision, and diplopia are seen.
  • Other organ infiltrations include testicular swelling and mediastinal compression.

“Role of abnormal myeloid cell proliferation in AML”

Acute myeloid leukemia Laboratory Findings

1. Blood picture

Anemia

• It is generally severe, progressive, and normochromic in type.
• Moderate reticulocytosis up to 5% and few nucleated red cells may be present.

Thrombocytopenia

• The platelet count is less than 50 000/µL.
• Whenplateletcountis below20 000/µL serious spontaneous hemorrhagic episodes develop.
• Acute promyelocytic leukemia (M3) may be associated with a serious coagulation abnormality called disseminated intravascular coagulation.

White Blood Cells

• In advanced cases, the WBC count is more than 100 000/µL.
• The majority of leucocytes in the peripheral blood blasts and there is often neutropenia due to marrow infiltration by leukemic cells.
• Some patients of myelodysplastic syndrome present with pancytopenia and have a few blasts labeled sub-leukemic leukemia or have no blasts labeled as aleukemic leukemia.

“Early warning signs of untreated acute myeloid leukemia”

2. Bone Marrow Examination

• Cellularity: Typically the marrow is hypercellular with a predominance of myeloblasts and promyelocytes. A dry tap may also occur due to pancytopenia or the adhesive nature of leukemic cells which are enmeshed in reticulin fibers.
• Leukemic cells: Diagnosis of the type of leukemic cells is done by routing Romanowsky stains and cytochemical stains. The presence of at least 30% blasts in the bone marrow is the essential criterion for the diagnosis of acute leukemia.
• Erythropoiesis: Erythropoietic cells are reduced. Dyserythropoiesis, megaloblastic features, and ring sideroblasts are common.
• Megakaryocytes: They are usually reduced or absent.
• Cytogenetics: 75% of cases show karyotypic abnormalities in the dividing leukemic cells

The common chromosomal abnormalities inAML are as follows:

• Aneuploidy: Hypo and hyperdiploid cell lines are found with equal frequency in AML.
• Philadelphia chromosome: 25-30% of cases of AML in adults show the Philadelphia chromosome. It is associated with poor prognosis.

“Asymptomatic vs symptomatic stages of AML progression”

3. Cytochemistry

• Myeloperoxidase: It is positive in immature myeloid cells containing granules and Auer rods, i.e. all forms of AML from mL to M6 but negative in M0 myeloblasts.
• Sudan black: Positive in immature cells in AML.
• Periodic acid-SchiffPAS): Positive in erythroleukemia (M6)
• Nonspecific esterase: Positive in monocytic series (M4 and M5)
• Acid phosphatase: Diffse reaction in monocytic cells (M4 and M5).

• Acute Myeloid Leukemia types

“Steps to educate patients about acute myeloid leukemia and its risks”

4. Biochemical Investigations

• Serum muramidase: Serum levels of lysozyme, i.e. muramidase are elevated in myelomonocytic (M4) and monocytic (M5) leukemia.
• Serum uric acid: Serum uric acid level is frequently increased because of a rapidly growing number of leukemic cells.