Chapter 96 • Leukemia is the most common childhood cancer. • The most common subtype, acute lymphoblastic leukemia (ALL), accounts for 75% to 80% of all cases of childhood leukemia, whereas acute myeloid leukemia (AML) comprises approximately 20%. • Chronic myelogenous leukemia (CML), myelodysplastic syndrome (MDS), and myeloproliferative disorder (MPD) are less frequent. • Males are generally affected by leukemia slightly more often than females in all age groups except infants. • In developed countries, the incidence of ALL is highest between ages 2 and 5 years. • The incidence of AML is relatively constant during childhood, with slight peaks in the first 2 years of life and in late adolescence. • MDS typically occurs after 5 years of age and juvenile myelomonocytic leukemia (JMML) occurs nearly always before 5 year of age. • Physical signs and symptoms of thrombocytopenia and anemia are common. • Neutropenia may lead to severe infection. • Bone pain and arthralgia caused by leukemic infiltration is more common in ALL than AML and may be especially severe in young children. • Common sites of extramedullary involvement in ALL include liver, spleen, thymus, and lymph nodes. • Skin, gums, and the head and neck area are typical sites of extramedullary disease in AML Infiltration of the central nervous system can be found in both ALL and AML. • The acute onset of petechiae, ecchymoses, and bleeding may suggest idiopathic thrombocytopenic purpura. • Both acute leukemia and aplastic anemia may present with pancytopenia and complications associated with bone marrow failure. • Infectious mononucleosis and other viral infections can be confused with ALL. • Bone pain, arthralgia, and occasionally arthritis may mimic juvenile rheumatoid arthritis, rheumatic fever, other collagen diseases, or osteomyelitis. • Childhood ALL should also be distinguished from pediatric small round cell tumors that involve the bone marrow.
Childhood Leukemia
Summary of Key Points
Incidence
Epidemiology
Clinical Findings
Differential Diagnosis
Childhood Leukemia
