Leukemia, Acute Lymphoblastic (ALL) in Adults



  • ALL in adults is the result of a clonal proliferation, survival, and impaired differentiation of immature lymphocytes. The World Health Organization (WHO) defines ALL as the presence of ≥25% lymphoblasts in the bone marrow, and the National Comprehensive Cancer Network (NCCN) uses a ≥20% as cutoff.
  • ALL and lymphoblastic lymphoma (LBL) can arise from same precursor cell line and be considered diseases along the same spectrum:
    • LBL presents as a mass, possibly, but not limited to, the mediastinum, with <25% blasts in the bone marrow.
    • ALL may present with a mass lesion but contains ≥25% bone marrow involvement.
  • Any organ can be affected.

Pregnancy Considerations
Many chemotherapy (CTX) drugs are teratogenic.

Pediatric Considerations
ALL is the most common malignancy in children—it accounts for 30% of all pediatric malignancies and 80% of pediatric leukemias (see “Acute Lymphoblastic Leukemia, Pediatric”).

Geriatric Considerations
Patients >60 years with ALL have a 42% mortality during induction CTX. The cause of death is usually CTX-related complications or relapse. Survival is often reduced due to poor tolerance of CTX, thus leading to dose reductions and ineffective medication delivery.



  • Incidence of ALL is 1.8/100,000 per year.
  • Higher incidence in older age, males, whites, those with history of radiation, CTX, or certain genetic disorders


  • Prevalence of ALL can range from 15% to 50% and increases with age.
  • Bimodal distribution: early peak in childhood, second peak at around age 50
  • 75–80% of cases occur in children, approximately 20% in adults.

Etiology and Pathophysiology

The pathophysiology of ALL involves the abnormal proliferation and differentiation of clonal lymphoid cells.


  • Higher rates in monozygotic and dizygotic twins
  • Increased risk of ALL with diseases related to chromosomal instability and inherited chromosomal abnormalities

Risk Factors

  • Age >70 years, radiation and CTX exposure, and infection with HIV are risk factors for developing ALL.
  • Human T-cell lymphotropic virus type 1 is associated with adult T-cell ALL.
  • Epstein-Barr virus is associated with mature B-cell ALL.

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