Definition/General
Introduction:
Acute lymphoblastic leukemia (ALL) is a malignant disorder of lymphoid precursor cells
It is characterized by clonal proliferation of immature lymphoblasts
ALL accounts for 80-85% of childhood leukemias
It represents 15-20% of adult acute leukemias.
Origin:
Arises from early lymphoid precursors in bone marrow
B-cell lineage (85% of cases)
T-cell lineage (15% of cases)
Results from genetic abnormalities affecting normal differentiation
Clonal expansion of arrested precursors.
Classification:
WHO classification based on immunophenotype and genetics
B-lymphoblastic leukemia/lymphoma
T-lymphoblastic leukemia/lymphoma
Further subclassified by cytogenetic abnormalities
Risk stratification based on molecular features.
Epidemiology:
Bimodal age distribution: Peak at 2-5 years
Second peak in elderly >50 years
Slight male predominance
Incidence: 3-4 per 100,000 children
Higher in Hispanic and Caucasian populations.
Clinical Features
Presentation:
Pancytopenia symptoms
Anemia (fatigue, pallor)
Thrombocytopenia (bleeding, petechiae)
Neutropenia (infections)
Organomegaly (liver, spleen, lymph nodes)
CNS involvement (5-10%).
Symptoms:
Fatigue and weakness (anemia)
Fever and infections (neutropenia)
Easy bruising and bleeding (thrombocytopenia)
Bone pain (leukemic infiltration)
Headache (CNS involvement)
Weight loss.
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Gross Description
Microscopic Description
Immunohistochemistry
Molecular/Genetic
Differential Diagnosis
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
[bone marrow aspirate/biopsy], [site], [cellularity]%
Blast Percentage
Blasts comprise [X]% of nucleated cells
Blast Morphology
[Size] lymphoblasts with [nuclear features] and [cytoplasmic features]
Immunophenotype
[B/T]-lymphoblastic leukemia: TdT+, [lineage markers]
Flow Cytometry
Positive: [markers], Negative: [markers]
Cytogenetics
Karyotype: [normal/abnormal], [specific abnormalities]
Molecular Studies
[Gene fusion/mutation]: [present/absent]
Risk Stratification
Risk group: [standard/intermediate/high] based on [factors]
MRD Monitoring
MRD monitoring by [flow cytometry/molecular] recommended
Final Diagnosis
Final diagnosis: [B/T]-lymphoblastic leukemia, [risk group]