Acute Myeloid Leukemia



Acute Myeloid Leukemia


Gladstone E. Airewele

C. Philip Steuber



EPIDEMIOLOGY

Acute myeloid leukemia (AML) represents approximately 20% of all leukemia diagnosed in children. In the United States, about 500 new cases are diagnosed annually in children less than 15 years old. Unlike acute lymphoid leukemia (ALL), the incidence of AML remains stable from birth until 10 years of age, and the disease occurs with equal frequency in boys and girls and in the various ethnic groups. The factors that lead to the development of AML are unknown in the overwhelming majority of cases, but certain conditions and exposures are known to predispose to AML (Box 301.1). In general, AML cells are more resistant to chemotherapy compared to ALL, and the therapy for childhood AML has not reached the degree of success achieved for ALL. Nevertheless, major therapeutic improvements have occurred in the last 20 years, and the overall long-term survival now approaches 50% to 60% in some studies. This improvement has been due largely to clinical trials conducted by various childhood cancer treatment groups and also to improvement in general supportive-care capabilities.


PATHOPHYSIOLOGY

AML is the result of a clonal proliferation of a hematopoietic precursor cell. The abnormal proliferation results in an accumulation of immature myeloid cells that are incapable of differentiating into mature cells. Although the precise pathophysiology of AML development is not completely understood, as in other malignancies, this abnormal proliferation results from a series of mutations affecting genes that are responsible for regulating the proliferation and differentiation of the hematopoietic stem cell. The term AML includes a variety of leukemia subtypes that are designated by apparent cell of origin (Table 301.1).








TABLE 301.1. THE FAB CLASSIFICATION SYSTEM WITH TYPICAL IMMUNOPHENOTYPING


























































FAB Type Morphologic Designation Relative Frequency Histochemistry Typical Immunophenotyping [CD, Cluster Designation]
M0 Myeloblastic leukemia–minimally differentiated <5% MPO SB NSE PAS Myeloid markers: [CD13, CD33, CD34]+ T-cell markers: [CD2, CD3, CD7]+ or B-cell markers: [CD10, CD19, CD20]
M1 Myeloblastic leukemia–without maturation 15–20% MPO+ SB+ NSE PAS Myeloid markers: [CD13, CD33, CD34]+ T-cell markers: [CD2, CD3, CD7]+ or B-cell markers: [CD10, CD19, CD20]
M2 Myeloblastic leukemia–with maturation 25–30% MPO+ SB+ NSE PAS Myeloid markers: [CD13, CD33, CD34]+ T-cell markers: [CD2, CD3, CD7]+ or B-cell markers: [CD10, CD19, CD20]
M3 Promyelocytic leukemia 5–10% MPO+ SB+ NSE PAS Myeloid markers: [CD13, CD33, CD34, CD117]+ T-cell markers: [CD2, CD3, CD7]+ or B-cell markers: [CD10, CD19, CD20]
M4 Myelomonocytic leukemia 25–30% MPO+ SB+ NSE+ PAS Myeloid markers: [CD11b, CD13, CD14, CD33, CD34]+ T-cell markers: [CD2, CD3, CD7]+ or B-cell markers: [CD10, CD19, CD20]
M5 Monocytic leukemia 15–20% MPO+ SB+ NSE+ PAS Myeloid markers:[CD 11b, CD13, CD14, CD33, CD34]+ T-cell markers:[CD2, CD3, CD7]+ or B-cell markers:[CD10, CD19, CD20]
M6 Erythroleukemia <5% MPO SB NSE+ PAS+ Myeloid markers: [CD13, CD33, CD34]+ T-cell markers: [CD2, CD3, CD7]+ B-cell markers: [CD10, CD19, CD20] Erythroid marker: Glycophorin A +
M7 Megakaryoblastic 5–10% MPO SB NSE+ PASPlatelet peroxidase+ Myeloid markers: [CD13, CD33, CD34]+ T-cell markers: [CD2, CD3, CD7]+ B-cell markers: [CD10, CD19, CD20] Megakaryocytic markers: [CD41/61, CD42]+
MPO, myeloperoxidase; SB, Sudan black; NSE, nonspecific esterase; PAS, periodic acid-Schiff.

Jul 24, 2016 | Posted by in ORTHOPEDIC | Comments Off on Acute Myeloid Leukemia
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