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Questions and Answers
Which gene mutation is predominantly associated with childhood B-ALL?
Which gene mutation is predominantly associated with childhood B-ALL?
- PTEN gene
- NOTCH1 gene
- PAX5 gene (correct)
- BCR gene
What is hyperdiploidy in the context of B-ALL?
What is hyperdiploidy in the context of B-ALL?
- Having a diploid number of chromosomes (46)
- Having fewer than 46 chromosomes
- Having a normal karyotype
- Having more than 50 chromosomes (correct)
Which translocation is most commonly associated with adult B-ALL?
Which translocation is most commonly associated with adult B-ALL?
- Translocation between chromosomes 12 and 21
- Translocation of ETV6 and TUNX1
- Translocation of NOTCH1 and CDKN2A
- Translocation of ABL and BCR (correct)
What are Auer rods indicative of in terms of leukemic classification?
What are Auer rods indicative of in terms of leukemic classification?
Which surface marker is primarily used to identify immature B cells in leukemia diagnosis?
Which surface marker is primarily used to identify immature B cells in leukemia diagnosis?
What clinical feature is commonly seen in leukemic infiltration in both ALL and AML?
What clinical feature is commonly seen in leukemic infiltration in both ALL and AML?
Which of the following is a common complication in T-ALL due to mediastinal mass formation?
Which of the following is a common complication in T-ALL due to mediastinal mass formation?
Which two genes are primarily mutated in T-ALL?
Which two genes are primarily mutated in T-ALL?
What classification applies if dysplasia is identified in the context of AML?
What classification applies if dysplasia is identified in the context of AML?
What is the minimum percentage of myeloblasts required in peripheral blood or bone marrow for an AML diagnosis?
What is the minimum percentage of myeloblasts required in peripheral blood or bone marrow for an AML diagnosis?
Which feature is characteristic of myeloblasts in the classification of AML?
Which feature is characteristic of myeloblasts in the classification of AML?
What defines myelodysplastic syndromes (MDS)?
What defines myelodysplastic syndromes (MDS)?
Which cell marker is NOT typically expressed on myeloblasts?
Which cell marker is NOT typically expressed on myeloblasts?
How does the prognosis of AML compare to that of acute lymphoblastic leukemia (ALL)?
How does the prognosis of AML compare to that of acute lymphoblastic leukemia (ALL)?
Which of the following is true about B-ALL?
Which of the following is true about B-ALL?
Which characteristic differentiates T-ALL from B-ALL?
Which characteristic differentiates T-ALL from B-ALL?
Which of the following classifications of acute myeloid leukemia (AML) is associated with a very poor prognosis due to occurrence after chemotherapy or radiotherapy?
Which of the following classifications of acute myeloid leukemia (AML) is associated with a very poor prognosis due to occurrence after chemotherapy or radiotherapy?
What is the initial step in the diagnostic process for acute myeloid leukemia (AML) when determining its classification?
What is the initial step in the diagnostic process for acute myeloid leukemia (AML) when determining its classification?
In acute myeloid leukemia (AML), what does dysplasia refer to in the context of cellular morphology?
In acute myeloid leukemia (AML), what does dysplasia refer to in the context of cellular morphology?
Which mutation is commonly associated with the development of epigenetic changes in acute myeloid leukemia (AML)?
Which mutation is commonly associated with the development of epigenetic changes in acute myeloid leukemia (AML)?
What differentiates acute myeloid leukemia (AML) from acute lymphoblastic leukemia (ALL) regarding their cellular infiltration?
What differentiates acute myeloid leukemia (AML) from acute lymphoblastic leukemia (ALL) regarding their cellular infiltration?
What is the significance of checking for translocations in the karyotype during the diagnosis of AML?
What is the significance of checking for translocations in the karyotype during the diagnosis of AML?
What type of cell counts are typically low in patients with acute myeloid leukemia (AML) leading to increased susceptibility to infections?
What type of cell counts are typically low in patients with acute myeloid leukemia (AML) leading to increased susceptibility to infections?
Which of the following features is primarily evaluated to confirm the diagnosis of acute myeloid leukemia (AML) after ruling out translocations?
Which of the following features is primarily evaluated to confirm the diagnosis of acute myeloid leukemia (AML) after ruling out translocations?
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Study Notes
Dysplasia
- Abnormal development or growth of tissues or organs
- Can include changes in the size, shape, and organization of cells
- Can be a precursor to cancer
Myelodysplastic Syndromes (MDS)
- Group of clonal stem cell disorders
- Associated with maturation defects and ineffective hematopoiesis
- High risk of transformation to AML
AML with Myelodysplasia
- Classified as AML with myelodysplasia if dysplasia is identified
- Can occur de novo or develop from complicated MDS
AML-Not Otherwise Specified
- Designated as AML-Not otherwise Specified if none of the previous classifications apply
AML Diagnosis
- Diagnosis based on 20% or more myeloblasts in peripheral blood or bone marrow (of nucleated cells)
AML Morphology
- Myeloblasts are large with a high nucleus to cytoplasm ratio
- Fine granules containing myeloperoxidase in the cytoplasm
- Fine and pale chromatin
- Prominent nucleoli
Auer Rods
- Small pink, needle-shaped rods present in cytoplasm
- Represent peroxidase enzyme
- Do not appear in lymphoblasts
AML Surface Markers
- Myeloblasts express several surface markers
- CD34: Present only on blast cells (myeloblasts or lymphoblasts), indicates an immature cell
- Myeloperoxidase (MPO): Found in granules or Auer rods; not expressed in lymphoblasts
- CD13 and CD33: Commonly expressed in myeloblasts
AML Outcome
- Generally poor outcome
- Worse than ALL (acute lymphoblastic leukemia)
ALL (Acute Lymphoblastic Leukemia)
- Refers to both acute lymphoblastic leukemia and lymphoma
- Aggressive neoplasms
- Express CD34 and TDT
B-ALL (B-cell ALL)
- Most common childhood malignancy
- Disseminates to solid organs (brain, testis, spleen)
T-ALL (T-cell ALL)
- Less common than B-ALL
- Presents in adolescents
- Involves Thymus, bone marrow, and blood
- More common in boys
ALL Symptoms
- Accelerated symptoms become significant within a few weeks
- Anemia: Fatigue and weakness
- Thrombocytopenia: Increased bleeding and bruising
- Neutropenia: Increased susceptibility to infections
AML Pathogenesis
- Mutations in genes of transcription factors required for maturation and differentiation of myeloblasts
- Interferes with differentiation of early myeloid cells
- Accumulation of myeloid precursors (blasts) in the marrow
- Additional mutations in tyrosine kinase pathways (RAS)
- Epigenetic mutation (changes in gene expression without changes to DNA sequence)
- Mutation in isocitrate dehydrogenase produces an oncometabolite (blocks the function of enzymes that regulate the epigenome and interferes with myeloblast differentiation)
WHO Classification of AML
- AML is heterogeneous
- Four types evaluated:
- Therapy-related AML: Occurs after treatment with chemo or radiotherapy
- AML with recurrent cytogenetic mutation: Genetic aberrations present, specific translocations are common
- AML with myelodysplasia: Dysplasia is identified
- AML-Not otherwise specified: None of the previous classifications apply
B-ALL Pathogenesis
- Mutation in PAX5 gene
- Mutations in RAS signaling and tyrosine kinase proteins promoting cell survival
- Most childhood B-ALL have hyperdiploidy (>50 chromosomes in the cell) and a translocation involving ETV6 and TUNX1 genes
- Adult B-ALL exhibits a translocation between ABL and BCR genes, creating a new tyrosine kinase protein (imatinib)
T-ALL Pathogenesis
- Mutation in NOTCH1 gene (70% of cases)
- PTEN gene (tumor suppressor)
- CDKN2A (promotes cell cycle)
ALL Morphology
- Blasts are large, high N/C ration
- Chromatin is open (pale)
- Nucleolus sometimes present
- Cytoplasm is very minimal and not granular
- Auer rods not present
ALL Flow Cytometry
- TdT: Immature cell marker
- CD22: B cell marker
- CD19: B cell marker
- CD10: Used as a marker of malignant B cells
- CD3: Indicates a T-cell malignancy
ALL Clinical Features
- Anemia, thrombocytopenia
- Bone pain, lymphadenopathy, hepatosplenomegaly, testicular enlargement
- Damage to solid organs due to leukemic infiltration
- CNS involvement (meningeal spread)
AML vs. ALL
- AML tends to remain in the bloodstream and bone marrow, unlike ALL which infiltrates tissues
- Myeloid sarcoma (acute monoblastic leukemia) is rare and occurs when AML infiltrates lymph nodes, spleen, and solid organs
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