⁨⁨⁨⁨⁨أسئلة المحاضرة السادسة أورام باطنة الدلتا

Leukemia Overview

• Leukemia is a malignant blood cell disease affecting white blood cells (WBCs), red blood cells (RBCs), and platelets (PLTs), mainly WBCs.
• It is the most common malignant disease in children.
• Acute lymphoblastic leukemia (ALL) accounts for approximately 75% of leukemia cases.
• Acute myeloid leukemia (AML) accounts for approximately 15-20% of cases.
• Chronic myeloid leukemia (CML), acute undifferentiated leukemia (AUL), and acute lymphoblastic acute myeloid leukemia (AMLL) account for approximately 5% of cases.
• Chronic lymphocytic leukemia (CLL) is not typically seen in children.
• ALL is the most common type of leukemia in children.

Etiology

• The causes of leukemia are multifactorial.
• Predisposing factors include chemical exposure, radiation, pollution, genetic disorders (e.g., Down syndrome), and viral infections.

Pathogenesis

• Leukemia is characterized by the uncontrolled proliferation of immature blood cells (blasts) in the bone marrow.
• This immature cell proliferation stops maturation of blast cells, increasing the number of blast cells in the bone marrow at the expense of other cell types.

Clinical Picture

• Common clinical manifestations include pallor (due to low red blood cell count), purpura (due to low platelet count), fever (due to low white blood cell count), and generalised lymphadenopathy.
• These characteristics may not always appear together.
• Other potential signs include splenomegaly, hepatomegaly, central nervous system (CNS) involvement, facial palsy, testicular infiltration, bone pain, arthralgia or arthritis, and unexplained fever or weight loss.
• Suspect leukemia if unexplained fever, anemia, or purpura are present.

Investigations

• Complete blood count (CBC) and blood film are used for the initial diagnosis.
• CBC can indicate anemia, thrombocytopenia, and leukocytosis (elevated WBC count) or more rarely leukopenia (low WBC count).
• Blast cells may be present in the blood film.
• WBC count greater than 50,000/µL is often associated with a poorer prognosis.
• Hyperleukocytosis (WBC count > 100,000/µL) is also a poor prognostic indicator.

Diagnosis of Leukemia

• Bone marrow aspiration is essential for diagnosing leukemia.
• The test looks for an increased percentage of blast cells in the bone marrow.
• The normal bone marrow blast count is less than 5%.
• If the suspected blast percentage in the bone marrow aspiration is 5–25%, repeat the test after two weeks to see if the blast cell percentage has progressed to above 25%.

Subtypes of Leukemia

• By cytochemical study with different stains like P.A.S. and acid phosphatase to further classify leukemia.

• Leukemia subtypes are classified using the French-American-British (FAB) classification system, typically based on the morphological characteristics of the cancerous white blood cells.

  • ALL encompasses subtypes like L1, L2, and L3 based on the appearance.
  • AML comprises subtypes such as M0-M7 as well.

Flowcytomertic and Cytogenetic Tests

• Flowcytomertic tests are used to classify leukemia based on the surface antigens on the blasts.
• Examples include CD markers (CD19, 22, 79a, and 10) for Pre B-ALL, and CD2,3,5,7 for T-ALL.
• Cytogenetic tests (e.g., detecting certain translocations) are also used for specific diagnostics, with specific outcomes considered favorable (e.g., t(12,21)), and others unfavorable (e.g., t(9,22), 11q23).

Other Investigations

• Other investigations, such as chest X-ray (CXR), abdominal ultrasound (Abdominal U/S), liver function tests, and kidney function tests, may be performed to aid in the assessment of other organ systems.
• Serum uric acid, immunophenotyping and cytogenetic studies are also important.

Bad Prognostic Criteria (ALL)

• Age, less than one year or greater than ten years.
• Male sex
• Black race
• White blood cells (WBCs) greater than 50,000 per \µm3.
• Severe thrombocytopenia.
• Mediastinal lymph node enlargement
• Huge Splenomegaly

Risk Group Stratification

• The Children Oncology Group (COG) criteria categorizes leukemia patients into different risk groups based on their initial white blood cell count and the absence or presence of extramedullary disease manifestation or involvement like CNS.

Treatment and relapse

• Treatment options for leukemia usually involve induction regimens, CNS prophylaxis, and maintenance therapy.
• Relapse can involve medullary, CNS, and/or testicular relapses.
• Differential diagnoses for similar symptoms include pancytopenia, purpura, arthritis, and hepatosplenomegaly (HSM). Additional differential diagnoses include conditions like lymphadenopathy, fever of unknown origin (FUO), and pallor.