[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [White cells, lymph nodes, spleen and thymus](https://durgical.com/en/general-pathology/areas/hematolymphoid/) › Acute lymphoblastic leukaemia/lymphoma

# Acute lymphoblastic leukaemia/lymphoma

- Lesion

The commonest childhood cancer: immature lymphocytes fill the marrow and push out normal blood cells. Most children are cured.

Updated Nov 12, 2026

## Key points

- About 80–85% are B-ALL; T-ALL often presents with a mediastinal mass that can compress the airway or superior vena cava.
- TdT is positive in most cases; B-ALL is CD19 and PAX5 positive, usually CD10 positive; T-ALL is CD3 positive.
- Good prognosis in children: hyperdiploidy and t(12;21) ETV6::RUNX1. Poor prognosis: infants with KMT2A rearrangements, adults, t(9;22) BCR::ABL1, hypodiploidy.
- Most T-ALL have activating NOTCH1 mutations.
- Down syndrome raises the risk of acute leukaemia.

## What it is

Acute lymphoblastic leukaemia/lymphoma (ALL/LBL) is a neoplasm of precursor B or T cells (lymphoblasts). B-ALL is mostly a disease of young children and presents as leukaemia; T-ALL affects adolescent boys more often and frequently presents as a thymic mass. The blasts replace the marrow, causing anaemia, infections and bleeding, and infiltrate bone, nodes, spleen, liver, CNS and testes. Genetic subgroups strongly predict outcome.

## Structure

- Marrow: hypercellular, replaced by lymphoblasts with scant blue cytoplasm, finely stippled chromatin and small nucleoli.
- Lymphoblasts are myeloperoxidase-negative and may contain PAS-positive cytoplasmic material.
- Lymphoblastic lymphoma of the thymus: diffuse sheets of blasts with many mitoses and a starry-sky pattern.

## Step by step

- A B- or T-cell precursor acquires a lesion that blocks differentiation, usually in a lineage transcription factor (PAX5, ETV6, RUNX1, NOTCH1 in T-ALL).
- Cooperating mutations, often in tyrosine kinase signalling, drive proliferation.
- Blasts accumulate in the marrow and crowd out normal haematopoiesis.
- Anaemia, thrombocytopenia and neutropenia appear within weeks.
- Blasts spread to nodes, spleen, liver, meninges, testes and, in T-ALL, the thymus.

## Markers

- TdT
- CD19
- CD10
- PAX5
- CD3
- CD7
- CD34

## Clinical notes

- Abrupt onset with fatigue, fever, bleeding, bone pain and tenderness, lymphadenopathy and hepatosplenomegaly.
- CNS involvement causes headache, vomiting and nerve palsies; sanctuary sites (CNS, testes) explain relapses.
- With modern therapy most children achieve remission and a large majority are cured.

## Memory aid

ALL: a child, a TdT-positive blast, and for T-ALL a mass in the chest.

## Test yourself

Think of the answer, then tap the question to see it.

## Which marker is positive in more than 95% of ALL?

TdT (terminal deoxynucleotidyl transferase).

## Which genetic changes carry a good prognosis in childhood B-ALL?

Hyperdiploidy and the t(12;21) ETV6::RUNX1 fusion.

## How does T-ALL often present?

In an adolescent male with a mediastinal (thymic) mass, sometimes compressing the airway or superior vena cava.

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## Elsewhere in DurgiPedia

- [Thymus: where T cells learn](https://durgical.com/en/immunology/thymus-where-t-cells-learn/)
- [Hematopoiesis and bone marrow](https://durgical.com/en/histology/hematopoiesis-and-bone-marrow/)

## Connections

## Related 4

- [Tumours of infancy and childhood](https://durgical.com/en/general-pathology/tumours-of-infancy-and-childhood/)
- [White-cell neoplasms: classification](https://durgical.com/en/general-pathology/white-cell-neoplasms-classification/)
- [Acute myeloid leukaemia](https://durgical.com/en/general-pathology/acute-myeloid-leukaemia/)
- [Chronic myeloid leukaemia](https://durgical.com/en/general-pathology/chronic-myeloid-leukaemia/)

## Related conditions 5

- [Acute leukaemia (AML and ALL)](https://durgical.com/en/conditions/acute-leukaemia/)
- [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/)
- [Mediastinal masses (thymoma and anterior mediastinal mass)](https://durgical.com/en/conditions/mediastinal-masses/)
- [Superior vena cava syndrome](https://durgical.com/en/conditions/superior-vena-cava-syndrome/)
- [Febrile neutropenia](https://durgical.com/en/conditions/febrile-neutropenia/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Childhood Acute Lymphoblastic Leukemia (PDQ®)–Patient Version](https://www.cancer.gov/types/leukemia/patient/child-all-treatment-pdq) (National Cancer Institute (NCI), 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/acute-lymphoblastic-leukaemia-lymphoma/