* This is the Professional Version. *

CONSUMERS: Tap here for the
Consumer Version

Overview of Leukemia

By Jerry L. Spivak, MD, Professor of Medicine and Oncology, Johns Hopkins University School of Medicine

NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version

The leukemias are cancers of the WBCs involving bone marrow, circulating WBCs, and organs such as the spleen and lymph nodes.

Etiology

Risk of developing leukemia is increased in patients with

History of exposure to ionizing radiation (eg, post–atom bomb in Nagasaki and Hiroshima) or to chemicals (eg, benzene)
Prior treatment with certain antineoplastic drugs, particularly procarbazine, nitrosureas (cyclophosphamide, melphalan), and epipodophyllotoxins (etoposide, teniposide)
Infection with a virus (eg, human T-lymphotropic virus 1 and 2, Epstein-Barr virus)
Chromosomal translocations
Preexisting conditions, including immunodeficiency disorders, chronic myeloproliferative disorders, and chromosomal disorders (eg, Fanconi anemia, Bloom syndrome, ataxia-telangiectasia, Down syndrome, infantile X-linked agammaglobulinemia)

Pathophysiology

Malignant transformation usually occurs at the pluripotent stem cell level, although it sometimes involves a committed stem cell with more limited capacity for self-renewal. Abnormal proliferation, clonal expansion, and diminished apoptosis (programmed cell death) lead to replacement of normal blood elements with malignant cells.

French-American-British (FAB) Classification of Acute Leukemias

FAB Classification	Description
Acute lymphocytic leukemia
L1	Lymphoblasts with uniform, round nuclei and scant cytoplasm
L2	More variability of lymphoblasts Sometimes irregular nuclei with more cytoplasm than L1
L3	Lymphoblasts with finer nuclear chromatin and blue to deep blue cytoplasm that contains vacuoles
Acute myelogenous leukemia
M1	Undifferentiated myeloblastic No cytoplasmic granulation
M2	Differentiated myeloblastic Sparse granulation in few to many cells
M3	Promyelocytic Granulation typical of promyelocytic morphology
M4	Myelomonoblastic Mixed myeloblastic and monocytoid morphology
M5	Monoblastic Pure monoblastic morphology
M6	Erythroleukemic Predominantly immature erythroblastic morphology, sometimes megaloblastic appearance
M7	Megakaryoblastic Cells with shaggy borders that may show some budding

Manifestations of leukemia are due to

Suppression of normal blood cell formation
Organ infiltration by leukemic cells

Inhibitory factors produced by leukemic cells and replacement of marrow space may suppress normal hematopoiesis, with ensuing anemia, thrombocytopenia, and granulocytopenia.

Organ infiltration results in enlargement of the liver, spleen, and lymph nodes and, occasionally, in kidney and gonadal involvement. Meningeal infiltration results in clinical features associated with increasing intracranial pressure (eg, cranial nerve palsies).

Findings at Diagnosis in the Most Common Leukemias

Feature	Acute Lymphocytic	Acute Myelogenous	Chronic Lymphocytic	Chronic Myelogenous
Peak age of incidence	Childhood	Any age	Middle and old age	Young adulthood
WBC count	High in 50% Normal or low in 50%	High in 60% Normal or low in 40%	High in 98% Normal or low in 2%	High in 100%
Differential WBC count	Many lymphoblasts	Many myeloblasts	Small lymphocytes	Entire myeloid series
Anemia	Severe in >90%	Severe in >90%	Mild in about 50%	Mild in 80%
Platelets	Low in > 80%	Low in > 90%	Low in 20 to 30%	High in 60% Low in 10%
Lymphadenopathy	Common	Occasional	Common	Infrequent
Splenomegaly	In 60%	In 50%	Usual and moderate	Usual and severe
Other features	Without prophylaxis, CNS commonly involved	CNS rarely involved Sometimes Auer rods in myeloblasts	Occasionally hemolytic anemia and hypogammaglobulinemia	Low leukocyte alkaline phosphatase level Philadelphia chromosome–positive in > 90%

Classification

Leukemias were originally termed acute or chronic based on life expectancy but now are classified according to cellular phenotype and degree of differentiation on initial presentation.

Last full review/revision January 2017 by Jerry L. Spivak, MD

Resources In This Article

Figure 1

Peripheral Blood Blast Cell
Figure 2

Acute Promyelocytic Leukemia
Figure 3

Acute Myelogenous Leukemia Without Maturation
Figure 4

Acute Lymphocytic Leukemia FAB Class L1
Figure 5

Acute Lymphocytic Leukemia FAB Class L2
Figure 6

Acute Lymphocytic Leukemia FAB Class L3
Figure 7

Blasts With Monocytic Differentiation
Table 1

French-American-British (FAB) Classification of Acute Leukemias
Table 2

Findings at Diagnosis in the Most Common Leukemias
Video 1

Overview of Acute Leukemia

Drugs Mentioned In This Article

Drug Name

Select Trade
teniposide

VUMON
etoposide

ETOPOPHOS
melphalan

ALKERAN
procarbazine

MATULANE
cyclophosphamide

CYTOXAN (LYOPHILIZED)

NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version

Secondary Iron Overload Acute Leukemia Overview

* This is the Professional Version. *

CONSUMERS: Tap here for the
Consumer Version

Professional Version

Commonly Searched Drugs

Recent News

PROCEDURES & EXAMS

Quizzes

Cases

Overview of Leukemia

Etiology

Pathophysiology

French-American-British (FAB) Classification of Acute Leukemias

Findings at Diagnosis in the Most Common Leukemias

Classification

Acute leukemias

Chronic leukemias

Myelodysplastic syndromes

Leukemoid reaction

Resources In This Article

Drugs Mentioned In This Article

Was This Page Helpful?

Commonly Searched Drugs

Recent News

PROCEDURES & EXAMS

Quizzes

Cases

Also of Interest

Overview of Leukemia

French-American-British (FAB) Classification of Acute Leukemias

Findings at Diagnosis in the Most Common Leukemias

Was This Page Helpful?

Also of Interest

Protein Intake Tied to Modest Survival Advantage in Breast CA

STUDENTSTORIES A MEDICAL EDUCATION BLOG

The Only “Real” Summer in Medical School

Time Hacks During Board Studying

STUDENTSTORIES
A MEDICAL EDUCATION BLOG