CH6 - 2) Acute Leukemia Flashcards
What is acute leukemia?
Neoplastic proliferation of blasts; defined as the accumulation of >20% blasts in the bone marrow.
What is the acute presentation for acute leukemia?
Anemia (fatigue), thrombocytopenia (bleeding), or neutropenia (infection)
What is the reason for the acute presentation of acute leukemia?
Increased blasts crowd-out normal hematopoiesis,
In acute leukemia, why is there a high WBC count?
Blasts usually enter the blood stream, resulting in a high WBC count
Describe blasts.
they are large, immature cells, often with punched out nucleoli
What is acute leukemia subdivided into?
acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML)
The subdivision of acute leukemia is based on what?
the phenotype of the blasts.
What is acute lymphoblastic leukemia?
Neoplastic accumulation of lymphoblasts (> 20%) in the bone marrow
Why is TdT useful in characterizing lymphoblasts?
It is absent in myeloid blasts and mature lymphocytes.
Acute lymphoblastic leukemia most commonly arises in whom?
children
What is acute lymphoblastic leukemia associated with and when does it usually arise?
Down syndrome (usually arises after the age of 5 years)
Acute lymphoblastic leukemia is subclassified into? What is it based on?
B-ALL and T-ALL based on surface markers
What is the most common type of ALL?
B-ALL
What is B-ALL usually characterized by?
lymphoblasts (TdT+) that express CD10, CD19, and CD20.
What is the treatment for B-ALL?
Excellent response to chemotherapy; requires prophylaxis to scrotum and CSf
What is the prognosis B-ALL based on?
It is based on cytogenetic abnormalities,
Which B-ALL has a good prognosis and is more commonly seen in children?
t(12;21)
Which B-ALL has a poor prognosis and in what population is it seen?
t(9;22) has a poor prognosis; more commonly seen in adults (Philadelphia+ALL)
What is T-ALL characterized by?
lymphoblasts (TdT+) that express markers ranging from CD2 to CDH (e.g., CD3, CD4, CD7). The blasts do not express CD10.
How does T-ALL usually present?
Usually presents in teenagers as a mediastinal (thymic) mass (called acute lymphoblastic lymphoma because the malignant cells form a mass)
What is acute myeloid leukemia?
Neoplastic accumulation of myeloblasts (> 20%) in the bone marrow
How are myeloblasts usually characterized?
by positive cytoplasmic staining for myeloperoxidase (MPO)
What may be seen in the characterization of myeloblasts?
Crystal aggregates of MPO may be seen as Auer rods
In whom does acute myeloid leukemia most commonly arise?
older adults (average age is 50-60 years)
What is the subclassification of AML based on?
cytogenetic abnormalities, lineage of myeloblasts, and surface markers.
What are the high-yield subtypes?
Acute promyelocytic leukemia, Acute monocytic leukemia and acute megakaryoblastic leukemia
What is acute promyelocytic leukemia characterized by?
t(15;17), which involves translocation of the retinoic acid receptor (RAR) on chromosome 17 to chromosome 15
What is the effect of RAR disruption?
It blocks maturation and promyelocytes (blasts) accumulate
How does acute promyelocytic leukemia lead to increased risk for DIC?
Abnormal promyelocytes contain numerous primary granules that increase the risk for DIC
What is the treatment for acute promyelocytic leukemia?
with all-trans retinoic acid (ATRA, a vitamin A derivative)
How does ATRA work?
It binds the altered receptor and causes the blasts to mature (and eventually die)
What is acute monocytic leukemia?
Proliferation of monoblasts; usually lack MPO
In acute monocytic leukemia what do blasts characteristically do?
infiltrate gums
What is acute megakaryoblastic leukemia?
Proliferation of megakaryoblasts; lack MPO
What is acute monocytic leukemia associated with?
Down syndrome (usually arises before the age of 5)
What is myelodysplastic syndrome?
acute myeloid leukemia may also arise from pre-existing dysplasia = myelodysplastic syndromes, especially with prior exposure to alkylating agents or radiotherapy
What do myelodysplastic syndromes usually present with?
cytopenias, hypercellular bone marrow, abnormal maturation of cells, and increased blasts < 20%
With myelodysplastic syndromes resulting in acute myeloid dysplastic syndrome what do most patients die from?
Most patients die from infection or bleeding, though some progress to acute leukemia.
