6.2 Acute Leukemia

Question 1

What is a simple definition of acute leukemia?

Answer 1

Neoplastic proliferation of blasts defined as having more than 20% blasts in the marrow
Divided into ALL or AML based on the phenotype of the blasts

Question 2

Why do acute leukemias present acutely?

Answer 2

They are a proliferation of blasts in the marrow. This crowds out normal hematopoiesis resulting in acute anemia (fatigue), thrombocytopenia (bleeding), or neutropenia (infection)

Question 3

What are the characteristic features of blasts?

Answer 3

Large, immature cells often with punched out nucleoli, and large nucleus/cytoplasm ratio

Question 4

What cells are neoplastic in ALL? What do they stain with that is characteristic?

Answer 4

Lymphoblasts (greater than 20% in marrow)

Positive nuclear staining for TdT (DNA polymerase), this is absent in myeloid blasts and mature lymphocytes

Question 5

Who gets ALL?

Answer 5

Commonly kids, associated with Down syndrome

Generally after 5 years of age

Question 6

What are the two subclassifications of ALL?

Answer 6

ALL is proliferation of lymphoblasts, these can be B cells or T cells dominant designated as: B-ALL or T-ALL

Question 7

Which acute leukemia is positive for TdT, and has cell markers CD10, 19, 20?

Answer 7

TdT=lymphoblasts
CD10, 19, 20 = B cells
Dx: B-ALL

Question 8

Which acute leukemia is TdT+, and has CD2-CD8 markers on cells?

Answer 8

TdT=lymphoblasts
CD2-8=T cells
Dx: T-ALL

Question 9

What is the outcome/prognosis of B-ALL?

Answer 9

Excellent response to chemo
Prognosis depends on cytogenic abnormalities:
t(12;21): good Px, common in kids
t(9;22): poor Px, common in adults (Philadelphia+ ALL)

Question 10

How does T-ALL usually present?

Answer 10

Teenagers as mediastinal (thymic) mass

Sometimes called: Acute Lymphoblastic Lymphoma because the malignant cells form a mass

Question 11

What cells proliferate in AML and what is their characteristic staining identifying feature?

Answer 11

Immature myeloid cells (greater than 20% in marrow)
Positive cytoplasmic staining for MPO (myeloperoxidase)

MPO can aggregate into crystals in the cytoplasm called Auer rods

Question 12

Who gets AML?

Answer 12

Older adults

50-60 years

Question 13

What are the subclassifications of AML?

Answer 13

Acute promyelocytic leukemia
Acute monocytic leukemia
Acute megakaryoblastic leukemia

Question 14

Acute promyelocytic leukemia

gene mutations, features, treatment

Answer 14

Subclass of AML
t(15;17) involves translocation of retinoic acid receptor on Chromosome 17 to 15
This blocks maturation and promyelocytes accumulate
Promyelocytes become myelocytes that produce granulocytes
The primary granules in the cells leads to risk of DIC
Treatment with all-trans-retinoic acid (ATRA)

Question 15

Acute monocytic leukemia

Answer 15

Subclass of AML
Proliferation of monoblasts
Usually lacks MPO!
Blasts characteristically infiltrate gums

Question 16

Acute megakaryoblastic leukemia

Answer 16

Subclass of AML but lacks MPO!
Proliferation of megakaryoblasts
Assoc. c Down Syndrome, usually before age 5

Question 17

What are the 2 acute leukemias associated with Down Syndrome and when do they present generally?

Answer 17

ALL after age 5

Acute megakaryoblastic leukemia before age 5

Question 18

Which of the acute leukemias has Auer rods?

Answer 18

Acute promyelocytic leukemia (type of AML)

Question 19

Which of the acute leukemias likes to infiltrate the gums?

Answer 19

Acute monocytic leukemia (type of AML)

Question 20

Exposure to what can lead to myelodysplastic syndromes and potentially AML?

Answer 20

People with myelodysplastic syndromes and with exposure to alkylating agents or radiotherapy can progress to AML