Overview
Definition
A clonal neoplastic disease of lymphoid progenitor cells (lymphoblasts), characterized by uncontrolled proliferation in the bone marrow and infiltration of extra-medullary sites (CNS, testes).
Epidemiology
The most common pediatric malignancy (peak age 2-5 years). Also occurs in adults (poorer prognosis).
Etiology & Risk Factors
- Acquired chromosomal translocations (e.g., t(12;21) in children, t(9;22) Philadelphia chromosome in adults)
Clinical Symptoms
- Fever, night sweats, weight loss
- Easy bruising and bleeding
- Bone pain (joint pain in children)
- Lymphadenopathy, hepatosplenomegaly
- CNS symptoms (headache, vomiting) due to meningeal infiltration
Clinical Approach
Diagnosis
- Bone marrow biopsy showing >= 20% lymphoblasts
- Flow cytometry distinguishing B-cell vs T-cell lineage
- LP to check for CNS involvement
Management
- Multi-agent induction, consolidation, and long-term maintenance chemotherapy
- Prophylactic intrathecal chemotherapy (methotrexate) to prevent CNS relapse
- TKIs (Imatinib) added for Philadelphia-chromosome positive ALL
- CAR-T cell therapy for relapsed/refractory cases
Complications
- CNS relapse
- Neutropenic sepsis
- Tumor lysis syndrome
- Avascular necrosis (from high-dose steroid therapy)