Pediatric emergency medicine trisk 2664 2664

• What does parent or patient believe to be the cause of the
problem?
CLINICAL PEARLS AND PITFALLS
Automated differentials may count leukemic blasts as either atypical
lymphocytes or monocytes so abnormal numbers of these cell types may
actually be due to leukemia.
Avoid aggressive transfusion in severely anemic but stable patients, as
this can result in rapid development of pulmonary edema and respiratory
failure.

Current Evidence
Leukemia is a cancer of white blood cells (WBCs) and their precursors that
proliferate in excess within the bone marrow and other hematopoietic tissues.
Leukemia is the most common childhood malignancy, accounting for 29% of all
cancer diagnoses in children from 0 to 14 years of age. Leukemias are classified as
either acute or chronic. More than 95% of pediatric leukemias are acute, with acute
lymphoblastic leukemia (ALL) accounting for the vast majority. The remaining
leukemias seen in children in order of decreasing frequency include acute myeloid
leukemia (AML), chronic myelogenous leukemia (CML), and juvenile
myelomonocytic leukemia (JMML). Specific classification is based on morphology,
immunologic surface markers, and cytogenetic abnormalities from the bone marrow
aspirate. Children with trisomy 21 are at increased risk of developing transient
abnormal myelopoiesis of the newborn, AML (younger than 4 years), and ALL
(older than 1 year).

Clinical Considerations
Clinical Recognition
The presentations of childhood leukemia are varied and, in some cases, the
diagnosis of leukemia is not at all obvious ( Table 98.2 ). Symptoms are usually
secondary to bone marrow replacement resulting in cytopenias or from
extramedullary infiltration of leukemic blast cells into tissues including the lymph

nodes, testes, liver, spleen, central nervous system (CNS), and skin. Systemic
symptoms such as fever and weight loss are common.
Patients with acute leukemia are at risk for serious hematologic, metabolic,
infectious, and cardiopulmonary complications. The patient with suspected leukemia
should be rapidly assessed for evidence of these complications.