Lecture 7 AML (select topics)

Question 1

What AML subtypes have pseudo pelger huet and hypo granulation as a lab finding?

Answer 1

M0, M1, M2

Question 2

What AML subtype features numerous abnormal promyelocytes? Describe some of their key features.

Answer 2

M3 and M3m (microgranular variant of M3)

Key features:
M3 - promyelocytes with heavy granulation, aurer rods may be seen, and kidney or bilobed shape nucleus.
M3m - nucleus is usually deeply notched or folded, butterfly, bi-lobed or kidney shaped. Cells appear devoid of granules or display a few. Auer rods occasioally. Note: Need Electron Mic to see.

Question 3

What complication of M3 and M3m is frequently encountered?

Answer 3

DIC

Question 4

What symtpoms are specific to M4, M4e, M5a&b? What other specific symptoms does M4 affect?

Answer 4

M4 & M4e: Soft tissue infiltrates due to monocytic component resulting in gum hypertrophy and infiltration, rectal ulcers, and skin involvement.

M5a&b: Skin and gum involvement.

M4: Meningeal symptoms: Headache, nausea, vomiting, blurring of vision and occasional intracranial hemorrhage.

Question 5

What systems are affected by the large monocytic involvement in M5a and M5b?

Answer 5

Extramedullary tissue masses and central nervous involvement.

High incidence of organ involvement of the AML subtypes!

Question 6

What can be measured in chemistry that supports the AML diagnosis for subtypes with a large monocytic component and why?

Answer 6

Serum and urine lysozyme are high because of monocytes.

Question 7

What AML subtype can be show positive with a PAS stain?

Answer 7

AML - M6 Erythroleukemia.

Question 8

What functional issue is common for all AML subtypes?

Answer 8

Functional abnormalities of granulocytes in phagocytosis, microbial killing, and chemotaxis resulting in increased
risk of infection.

Question 9

What other conditions can AML-M6 be confused with when looking at the morphology under the light microscope?

Answer 9

M6 can be confused with B12, folate deficiencies and
Myelodysplastic syndromes when diagnosing.

Question 10

What separates M2 from M1 subtypes of AML?

Answer 10

M2 has Type I, II, and III blasts where as M1 only has Type I and II. Both have Auer rods but M1 will only present in 50% of cases and in M2 they are often present. Also, M2 has > 10% granulocytes beyond the promyelocytes stage and <20% monocytic cells.

Question 11

What is the key difference between M4 and M2 subtypes of AML?

Answer 11

M4 has >20% of non-erythroid cells are monocytic whereas M2 it is <20%.

Question 12

What AML subtype has both abnormal granulocytic and monocytic differentiation observed in the peripheral blood and bone marrow? What is it called?

Answer 12

M4 - Acute Myelomonocytic Leukemia

Question 13

What AML subtype is associated with Eosinophilia and its criteria?

Answer 13

M4e

Eosinophils >5% of non-erythroid cells in marrow, separates it from M4.

Eosinophils are abnormal - immature, single lobed, unsegmented and may have large basophilic granules. Generaly these cells only seen in the marrow.

Question 14

What is another name for AML-M5?

Answer 14

Schilling Leukemia (with 2 types M5a and M5b).

It has the highest incidence of organ and soft tissue involvement due to monocytic component

Question 15

In what AML subtype could you find >80% of non-erythroid cells as monoblasts? Auer rods?

Answer 15

AML-M5a (poorly differentiated)

Auer rods may be present but less common than as with M1, M2, and M3.

Question 16

What AML subtype would you find the most predominate cell in the marrow promonocytes? What’s the predominant cell than in the blood?

Answer 16

AML-M5b (well differentiated).

Blood - monocyte.

Auer rods may be present. Less common than M1, M2, and M3.

Question 17

What are some of the RBC morphology that one can expect to find in a case of AML-M6 (Acute Erythroleukemia)?

Answer 17

RBC morphology (peripheral blood) displays large variety: anisocytosis,
poikilocytosis, macrocytosis with oval forms, schistocytes, dimorphic population. Numerous NRBCs.

Question 18

Can AML-M6 include myeloblasts in the bone marrow, if so what %? What about the erythrocytic component i the bone marrow?

Answer 18

Yes, >30% of non-erythroid cells are Type I and Type II Myeloblasts which may contain auer rods.

Over 50% of nucleated cells in the bone marrow are erthrocytic, i.e. erythroid hyperplasia.

Question 19

Describe the abnormal morphology associated with AML-M7 that one can find in the peripheral blood? PLT counts?

Answer 19

Megakaryocytic fragments and abnormal giant platelets.

Micromegakaryocytes, some with naked nuclei and groups of platelets surrounding them may be seen.

Platelet counts normal or increased

Question 20

What can be found in the bone marrow of AML-M7?

Answer 20

Acute Megakaryocytic Leukemia:

Bone marrow -
a) Frequent diffuse fibrosis.
b) Aggregates of Meagakaryoctyes.
c) Sheets of Megakaryoblasts.

Question 21

What AML subtype is associated with a poor prognosis and pancytopenia? How high can the blasts get in the bone marrow?

Answer 21

AML-M0

Blasts in the bone marrow may be as high as 90%. Although blasts generally present in the peripheral in most cases, but also may be absent.

Poor prognosis - Higher incidence of refractory to chemotherapy adn relaspe than other AML’s.

Question 22

What are typical symptoms of almost all AML’s?

Answer 22

AML rapidly fatal if untreated. Death due to pancytopenia such as anemia, bleeding and infection.