The diagnosis of childhood leukemia

1. Big picture

Childhood leukemia is the most common pediatric malignancy, and the key exam skill is early recognition from nonspecific symptoms.

A child with leukemia often does not present saying “I have cancer.” The child presents with:

Fever + pallor + bruising/petechiae + bone pain + lymphadenopathy/hepatosplenomegaly

The diagnostic logic is:

Unexplained cytopenia(s) or blasts on blood film
→ suspect leukemia
→ urgent pediatric hematology referral
→ stabilize emergencies first
→ confirm by bone marrow examination
→ classify by flow cytometry + cytogenetics/molecular testing
→ assess CNS/testicular/extramedullary involvement
→ risk stratify before treatment

The examiner wants to hear that diagnosis is not made only by white blood cell count. Some children have high WBC, some normal WBC, and some leukopenia. The decisive clue is bone marrow failure ± circulating blasts ± organ infiltration.

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