Lecture 8 Acute Lymphoblastic Leukemias

Question 1

What is Acute Lymphocytic Leukemia?

Answer 1

ALL is a hematological malignancy characterized by uncontrolled proliferation and accumulation of poorly differentiated (immature) lymphoid cells.

ALL starts with a lymphoid stem cell, immature T or B cell, and/or pluripotent cell mutation that transforms it to a malignant cell which does not respond to normal cytokine regulation and proliferates first in the bone marrow and then often spills into the peripheral blood.

Question 2

What are the general symptoms of Acute Lymphocytic Leukemia?

Answer 2

Symptoms usually occur quite suddenly.
1. Malaise, fatigue, SOB, and pallor due to anemia.
2. Thrombocytopenia causing bruising and bleeding can be present.
3. Frequent infections due to granulocytopenia demonstrated by fevers and chills.
4. Bone pain, sternal tenderness, swelling and tenderness of large joints due to leukemic cell infiltration.
5. Meningeal infiltration by leukemic cells can result in cranial nerve paralysis, increased intracranial pressure, eye hemorrhage.
6. Lymph node enlargement, splenomegaly and hepatomegaly.

Question 3

What is the number one cause of death for those with ALL?

Answer 3

Infection (neutropenia),
Risk is proportional to degree of granulocytopenia from either the marrow replacement by leukemic cells or chemotherapy (during treatment).

Question 4

What are the other causes of death for those with ALL after infection?

Answer 4

1. Bleeding (from thrombocytopenia)
2. Infiltration of liver by leukemic cells can decrease synthesis of Vitamin K dependent clotting factors causing increased risk of bleeding.

Question 5

What kind of anemia can occur in a small number of ALL cases? What is the characteristic of the problem?

Answer 5

DIC (a MAHA)
Results in patient first going into a thrombotic state producing clots which if not controlled exhausts the coagulation factors and platelets to the point where the patient is at risk of spontaneous bleeding (hemorrhagic). This is called a thrombotic/hemorrhagic state.

DIC is where fibers are laydown in the blood vessels and uses up clotting factors.

Question 6

What can the WBC count be in ALL?

Answer 6

In ALL the WBC count can be low, normal or high.

60% of cases, WBC>10
15% of cases, WBC>100
25% of cases, WBC <4.0

Question 7

What is the predominant cell circulating in the peripheral blood? What is the exception to this?

Answer 7

Lymphoid blast cell.

Except in aleukemic leukemia where the malignant cells stay in the marrow and few to none go into the peripheral blood.

Question 8

What are laboratory findings in the bone marrow for ALL?

Answer 8

1. Bone marrow almost always hypercellular and infiltrated by lymphoid blast cells.
2. Fibrosis (10-15% of cases)
3. Thrombocytompenia and anemia almost always present due to reduced normal marrow elements.

Question 9

What other diseases can cause lymphocytosis in the peripheral blood similar to ALL?

Answer 9

Pertussis
Infectious mononucleosis
Other viral illnesses.

Can produce lymphocytosis with fever, enlarged nodes and splenomegaly with marrow only minimally affected whereas in ALL the marrow is majorly affected.

Question 10

What is the difference between Adult ALL and cases that occur in children?

Answer 10

Adult ALL has
1. Higher WBC Count
2. Higher incidence of Philadelphia chromosome.
3. Type 2 morphology.

Question 11

What are the cytologic features for L1 ALL Lymphoblasts (cell size, chromatin, nuclear shape, nucleoli, amount of cytoplasm, basophilia of cytoplasm and cytoplasm vacuolation)?

Answer 11

Cell size: Small cells predominate (still 2X size of small lymphocyte)
Chromatin: Homogeneous in any one case
Nuclear shape: Regular, occasional clefting or indentation
Nucleoli: Not visible or small and inconspicuous (usually only 1)
Amount of cytoplasm: Scanty
Basophilia of cytoplasm: Slight or moderate, rarely intense
Cytoplasmic vacuolation: Variable.

Question 12

What are the cytologic features for L2 ALL Lymphoblasts (cell size, chromatin, nuclear shape, nucleoli, amount of cytoplasm, basophilia of cytoplasm and cytoplasm vacuolation)?

Answer 12

Cell size: Large, heterogeneous
Chromatin: Variable; heterogeneous in any one case
Nuclear shape: Irregular, clefting and indentation common
Nucleoli: One or more present, often large
Amount of cytoplasm: Variable; often moderately abundant
Basophilia of cytoplasm: Variable; deep in some
Cytoplasmic vacuolation: Variable.

Question 13

What are the cytologic features for L3 ALL Lymphoblasts (cell size, chromatin, nuclear shape, nucleoli, amount of cytoplasm, basophilia of cytoplasm and cytoplasm vacuolation)?

Answer 13

Cell size: Large and homogeneous
Chromatin: Finely stippled and homogeneous
Nuclear shape: Regular, oval to round
Nucleoli: Prominent; one or more; vesicular
Amount of cytoplasm: Moderately abundant
Basophilia of cytoplasm: Very deep
Cytoplasmic vacuolation: Often prominent

Question 14

Which type of ALL has the best prognosis and which one has the worst?

Answer 14

ALL-L1 has the best prognosis, whereas ALL-L3 has a poor prognosis.

Question 15

How are L2 and L1 type cell’s nucleus outline/shape different between each other?

Answer 15

L1 has a very homogeneous presenting nucleus/chromatin. L1’s nucleus is usually round and regular with only occasional clefting and indentation whereas L2 has nuclear with clefting, folding and indentation as common with gross irregularities present in some cases.

Question 16

How are L2 and L1 type cell’s different in size in ALL?

Answer 16

L1 is small (only 2x’s size of small lymphocyte) whereas L2 is a large cell.

Question 17

Which type of lymphoblast only has a scant cytoplasm in ALL and which one has a variable often moderately abundant cytoplasm?

Answer 17

ALL-L1 has a scant cytoplasm

ALL-L2 has a variable, often moderately abundant cytoplasm

Question 18

Which type of lymphoblast may have vesicular (rectangular) nucleoli in ALL?

Answer 18

ALL-L3

Question 19

How does L1 and L2 nucleoli differ from each other in ALL?

Answer 19

L1 has none nucleoli visible or are small and inconspicuous and then usually only 1.

L2 will have one or more nucleoli present that are often large.

Question 20

What are the key differentiating features of ALL-L3?

Answer 20

ALL-L3:
Basophilic cytoplasm with vacuolation of the cytoplasm and nucleus.

Question 21

What really are the vacuoles seen in L3 and why do they appear? Can they be seen in the nucleus?

Answer 21

The vacuoles are not really vacuoles in ALL-L3 lymphoblast cells but are lipid containing deposits demonstrated by Wright’s stain as clear spots.

Yes they can also be present in the nucleus - called nuclear vacuolation. Result of lipid deposits overlying the nucleus and appearing as vacuoles with Wright’s stain.

Question 22

What is Periodic Acid Schiff not helpful in differentiating L1 and L2? Why would it be used?

Answer 22

L1 and L2 are both strongly positive with PAS and therefore cannot be used to differentiate L1 from L2.
However L3 is PAS negative.

Question 23

What are the staining results for ALL with Sudan Black B (SBB) and Myeloperoxidase (MPO)?

Answer 23

SBB and MPO are generally negative in ALL however some ALL’s are weakly positive for SBB and some immature AML’s (M0) are negative for MPO .

Question 24

What is acid phosphotase used for? And its limitations?

Answer 24

Acid phosphotase is useful for differentiating T-Cell from B-Cell ALL (but not B-Cells from Myeloid Cells).

T-Cell shows stronger positivity with a localized pattern in the golgi region of the cell. However, B-Cell shows diffuse pattern which can also be present in Myeloid cells therefore not helpful for separating these two.

Question 25

What stain can be useful for differentiating T-Cell from M5 (AML)? How?

Answer 25

Non-specific esterase.
T-Cell strains focal paranuclear pattern while M5 stains as a diffuse pattern.

Question 26

What stain is useful for differentiating CML transformation to ALL? Why?

Answer 26

Terminal deoxynucleotidyl Transferase (TDT).

It is strongly positive in 90% of ALL patients.

Question 27

What is TDT?

Answer 27

TDT is an intranuclear DNA enzyme detected in both T and primitive B cells.

Question 28

How would Oil Red O staining of lymphoblasts vary from Wright’s stain?

Answer 28

Oil Red O stains the lipid collections so they no longer appear as vacuoles.

Question 29

What does the technique use for immunological markers in identifying ALL classificaitons?

Answer 29

Technique uses monoclonal antibodies to detect specific cell marker antigens via flow cytometry.

Very important for diagnosis and treatment.

Question 30

What are the notable lab finding and clinical findings with T-Cell (subtype) ALL?

Answer 30

T-Cell type associated with very high WBC count and increased incidence of CNS involvement.
50% of cases present with thymic mass.
Morphologically presents as L1 or L2 (but still need flow cytometry)

Question 31

What is Bilineage or Biphenotypic Leukemia?

Answer 31

Leukemias expressing both myeloid and lymphoid antigens on same cell - also known as “Mixed” leukemia.

Question 32

Why is it important to identify as Biphenotypic Leukemia?

Answer 32

Important to identify as Biphenotypic may not respond well to myeloid chemo treatment but usually does respond well to ALL treatment regimens.

Question 33

What are cytogenetic studies used for in ALL?

Answer 33

1. Used to predict therapeutic outcomes (prognosis)
2. Chromosomal abnormalities in 50% of cases.
3. Some translocations associated with specific ALL types.
4. Increase number of chromosomes (hyperploidy) present in some ALL’s. More frequent in children and indicate better prognosis.

Question 34

Why is it important to identify breakpoint regions of chromosomal abnormalities in diagnosing ALL?

Answer 34

Can relate to leukemic process and response to therapy.
E.g. ALL Philadelphia chromosome (PH+) breakpoint is different from CML and more resistant to therapy.

Question 35

How is molecular testing helpful in ALL diagnosis?

Answer 35

Molecular testing provides earlier detection of malignant T and B cells.
Also valuable to detecting small numbers of residual abnormal cells following completion of treatment.

Question 36

Prior to treatment what symptoms are patients generally treated for in ALL?

Answer 36

1. Packed cells for anemia
2. Platelets for thrombocytopenia
3. Antibiotics for infection

Question 37

What occurs in the past in 50% of children who relapsed? What do they do now?

Answer 37

CNS involvement due to leukemic cells present in meninges and CSF not affected by chemo treatment as those drugs cannot cross blood brain barrier.

Now children receive spinal chemo drug injection and cranial irradiation. Relapse now reduced to less than 5%.

Question 38

What is a side effect of chemo treatment in ALL?

Answer 38

Renal failure from increased uric acid resulting from destruction of large numbers of lymphoid cells due to chemo treatment is another condition which must be monitored.

Question 39

When is a bone marrow transplant considered for an ALL patient?

Answer 39

Refractory or high risk ALL and for patients who relapse and achieve remission.

Question 40

What cell types are good prognosis and what are poor prognosis?

Answer 40

Pro-B good prognosis in children.
T-Cell frequent thymic mass poor prognosis.

Question 41

What are the main causes of death in someone with ALL that has not been effectively treated or cured?

Answer 41

Death usually from infection or bleeding if not treated.