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Flashcards in Heme/Onc3 Deck (57):
1

What is (the definition of) acute leukemia?

A neoplastic proliferation of blasts; defined as >20% blasts in the bone marrow

2

What is the general idea behind acute leukemia?

In acute leukemia, the idea is that there is a disruption in the ability of bone marrow cells to mature, so that the myeloblast, or the lymphoblast, for example, loses the ability to become a more mature cell. When this happens, the precursor cell (the blast) begins to pile up.

3

What are the two general categories of acute leukemia?

(1) Acute Lymphoblastic Leukemia
(2) Acute Myelogenous Leukemia

based on the phenotype of the blasts

4

What are the clinical and lab findings of acute leukemia?

Increased blasts crowd-out normal hematopoiesis, resulting in:
--anemia (fatigue)
--thrombocytopenia (bleeding)
--leukopenia (infection)

Blasts enter the blood stream, resulting in a high WBC count

5

What do the blasts in acute leukemia look like on peripherla blood smear (or even bone marrow aspirate)?

(1) large
(2) immature (very little cytoplasm)
(3) punched out nucleoli

6

What is acute myelogenous leukemia?

A neoplastic accumulation of myeloblasts (>20%) in the bone marrow

7

By what stain can myeloblasts be characterized?

Positive cytoplasmic staining for myeloperoxidase (MPO)

8

What is a classic histologic finding of AML (particularly, the M3 subtype--acute promyelocytic leukemia)

Auer rods, which are crystal aggregates of MPO

9

What is the M3 subtype of AML?

acute promyelocytic leukemia

10

What is the M5 subtype of AML?

acute monocytic leukemia

11

What is the M7 subtype of AML?

acute megakaryocytic leukemia

12

What subtype of AML is characterized by a t(15;17) translocation? What is the translocation?

M3 - acute promyelocytic leukemia

This involves translocation of the retionic acid receptor (RAR) on chromosome 17 to chromosome 15.
RAR disruption blocks maturation and promyelocytes (blasts) accumulate.

13

With what genetic abnormality is acute promyelocytic leukemia (M3 subtype of AML) associated?

t(15;17) translocation

involves translocation of the retinoic acid receptor (RAR) on chromosome 17 to chromosome 15

14

A 35-yo woman comes to the physician because of several months of fatigue. Lab studies confirm the diagnosis of AML. She is placed on antileukemic therapy, but shortly after her first dose of chemotherapy, she develops brusing and bleeding, and she is diagnosed with DIC. What is the most likely subtype of AML in this patient? Why did she develop DIC?

M3.

This subtype of AML contains numerous Auer rods (granules), which are crystal aggregates of MPO. Auer rods can activate the coagulation cascade, leading to DIC.
Chemotherapeutic agents can trigger the release of these granules, leading to DIC.

15

How do you treat M3 AML?

with all-trans-retinoic acid (ATRA, a vitamin a derivative)

this binds to the altered recepter (RAR) and causes the blasts to mature to neutrophils (and eventually die)

16

What is acute monocytic leukemia?

a proliferation of monoblasts; the M5 subtype of AML

17

What is the classic presentation of the M5 subtype and why?

Patients will characteristically present with involvement of the gums; the blasts in M5 characteristically infiltrate the gums

18

What is acute megakaryoblastic leukemia?

a proliferation of megakaryoblasts; M7

19

What are the key associations in M7? (3)

--associated with Down syndrome (usually arises before the age of 5)
--these blasts lack MPO
--associated with myelofibrosis due to PDGF release

20

In what disease would we see a monoclonal spike on electrophoresis and rouleaux formation of PBS (peripheral blood smear)?

Multiple myeloma.

multiple myeloma results from a malignant proliferation of plasma cells in the bone marrow. These neoplastic cells produce immunoglobulin (seen as an M spike on electrophoresis), which increases the serum protein. This increased serum protein decreases the charge between the RBCs--instead of spreading themselves out evenly across the smear, they pile up on each other like poker chips. This is known as a Rouleaux formation.

21

A 60 year old woman comes to the physician because of weakness, fatigue and bruising. Her pulse is 110/min, blood pressure is 100/75 mmHG, and RR is 22. Physical exam shows pallor and petechial hemorrhages in the mouth. Labs show marked increased in white cells, anemia, and thrombocytopenia. A peripheral blood smear shows blasts with auer rods. What complication is likely to occur upon lysis of these cells induced by chemotherapy?

DIC

22

What is the difference in outcome between normal Warfarin dosing and warfarin overdose?

Appropriate warfarin dosing will usually only prolong the PT, because only factor 7 levels are decreased enough to impair coagulation. (Only the extrinsic pathway is affected)

In warfarin overdose, both the PT and the PTT are prolonged because all of the vitamin K-dependent factors (2,7,9,10) are decreased. Here, both the intrinsic and extrinsic pathways are affected.

23

Why is warfarin overdose particularly dangerous?

Because both the intrinsic and extrinsic pathways of the coagulation cascade are affected, there is no effective coagulation route that can be triggered if the patient starts to hemorrhage badly

24

In which disease do we see target cells?

**Thalassemias
--hemoglobin C disease
--asplenia (e.g., in sickle cell anemia w/ autosplenectomy)
--liver disease

25

What would you see on PBS with hereditary spherocytosis, and why?

Spherocytes--RBCs that have lost their concave shape and central pallor due to a decrease in the surface membrane.

Typically affected proteins are: spectrin and ankyrin

26

Why might we see Howell-Jolly bodies on a PBS in a patient with sickle cell anemia?

This is due to autosplenectomy, which is an irreversible complication of sickle cell disease.

Sickle cell exacerbations lead to repeated vaso-occlusive events that lead to repeated infarctions. This causes the spleen to become atrophic and shrunken. Patients become functionally asplenic.

27

Why is the spleen susceptible to autosplenectomy in patients with sickle cell anemia?

The spleen receives its blood supply from a single source. This lack of collateral circulation makes it prone to infarction from sickle cell disease.

28

Why would a sickle cell disease patient have hepatomegaly?

Extramedullary hematopoiesis.

In response to hemolysis and anemia, massive erythroid hyperplasia ensues, resulting in expansion of hematopoiesis into the skull and facial bones, as well as in extramedullary hematopoiesis in the liver.

29

In what patients would we see a crew-cut appearance on X-ray and "chipmuck facies" in patients and why?

Sickle cell disease

In response to hemolysis and anemia, massive erythroid hyperplasia ensues, resulting in expansion of hematopoiesis into the skull and facial bones, as well as in extramedullary hematopoiesis in the liver.

30

What types of infections are patients with sickle cell disease susceptible to and why?

(1) infection with encapsulated bacteria, due to loss of spleen function (autosplenectomy) (most common: H. influenza and S. pneumoniae)

(2) Parvovirus B19 infection of erythroid precursors, leading to an aplastic crisis

(3) Salmonella paratyphi osteomyelitis

31

A 4-year-old girl is brought to the emergency department because of a fever and severe pain in her fingers and toes. Treatment with morphine is begun and the girl's symptoms are partially alleviated. Physical examination shows a raised facial rash. A PBS shows severe anemia, and bone marrow aspirate show no erythroid precursor cells. What is the likely infecting agent? Given the agent, what is the girl's differential?

Parvovirus B19

32

What are the three syndromes that Parvovirus B19 can cause?

(1) Aplastic crisis in individuals with chronic hemolytic diseases (sickle cell, thalassemia)

(2) childhood febrile rash (erythema infectiosum)

(3) congenital infections that present as stillbirth, hydrops fetalis

33

Why are patients with Hairy Cell Leukemia prone to frequent infections.

This is due to decreased leukocytes. Unlike most forms of leukemia, HCL is characterized by pancytopenia rather than in increase in the number of circulating cells

34

What would you see on bone marrow aspiration with Hairy Cell Leukemia?

You would get a dry tap due to marrow fibrosis

35

With what leukemias is the Philadelphia chromosome associated? What is the translocation involved?

t(9;22)

(1) chronic myeloid leukemia (CML)
(2) acute lymphoblastic leukemia

36

Causes of microangiopathic hemolytic anemia

(1) DIC
(2) TTP
(3) HUS
(4) prosthetic heart valves

37

What would we see on PBS with chronic autoimmune gastritis, and why?

Abnormally large (macrocytic) RBCs and hypersegmented neutrophils.

Chronic autoimmune gastritis is associated with the production of antibodies that block the binding of intrinsic factor (produced by gastric parietal cells) to B12. This leads to impaired B12 absorption in the terminal ileum, resulting in a megaloblastic anemia.

38

A 34-year old woman develops sudden loss of consciousness, shortness of breath, and decreased urine output. Two days ago, she gave birth via vaginal delivery without complications. An ultrasound reveals retained placental tissue within the uterine fundus. A blood smear shows helmet cells. Labs show anemia and thrombocytopenia. What is the diagnosis? Why does this patient have loss of consciousness, SOB, and decreased urine output?

This patient has DIC.

The loss of consciousness, SOB, and decreased urine output are all related to the formation of microthrombi throughout the circulation.

39

A 60-year old man with a history of angina is brought to the ED because of severe chest pain unresponsive to subingual introglycerin. An ECG shows ST-segment elevation in the anterolateral leads. Treatment with streptokinase will have what affect and why?

Streptokinase will lead to thrombolysis (destruction of the clot) by binding to plasminogen and converting it to plasmin. Plasmin will then cleave cross-linked fibrin and fibrinogen. Plasmin also degrades factors V and VIII. Lysis of the clot will hopefully restore blood flow to the ischemia cardiac muscle.

Streptokinase is a urokinase-like plasminogen activator.

40

What is the key difference in the information that can be obtained from fibrin degradation products (FDPs) and D-dimers? (What makes them different?)

FDPs are generated from the breakdown of fibrin and fibrinogen, while D-dimers are generated exclusively from the breakdown of fibrin. D-dimers are therefore a much better indication of clot formation and destruction (and therefore a better indicator or thrombin and plasmin fucntion) than FDPs

41

When might we see an increase in fibrin degradation products (FDPs), but not in D-dimers?

This would result from the breakdown of fibrinogen, but not fibrin. This might occur when there is increased activity of plasmin outside the clotting cascade. This could result from descreased inhibition from alpha-2-antiplasmin, or from increased activity of urokinase, tPA, or streptokinase.

42

Besides DIC, what other disorders is D-dimer useful in diagnosing?

PE (pulmonary embolism)
DVT (deep vein thrombosis)

Any condition in which there is (pathologic) clot formation.

43

What is DiGeorge syndrome?

Autosomal dominant deletion on chromosome 22, resulting in failure of development of the 3rd and 4th pharyngeal pouches.

44

What are the manifestations of DiGeorge syndrome?

CATCH22

Cardia abnormalities
Abnormal facies
Thymic aplasia/ tetany(muscle twitches)
Cleft palate (philtrum)
Hypocalcemia
22- deletion on chromosome 22

45

What abnormal facies are seen in DiGeorge syndrome?

--hypertelorism (abnormally increased distance between two organs, usually the eyes)
--philtrum (vertical groove in the middle of the upper lip, below the septum of the nose)
--low-set ears
--micrognathia (aka mandibular hypoplasia; a condition where the jaw is undersized)

46

Why do we see tetany in DiGeorge syndrome?

This is ultimately due to the failure of development of the parathyroid glands.

Hypoparathyroidism --> hypocalcemia --> tetany/muscle twitching.

47

Why would DiGeorge patients not be able to develop allergy (type I hypersensitivity)?

Because of thymic aplasia.

Allergy is dependent upon the release of histamine from mast cells that occurs when surface IgE is crosslinked by allergens. IgE, however, can only be produced via class switching, which is dependent on cytokine signalling from Th2 cells. Because a patient with DiGeorge syndrome lacks a thymus (which is where T cells mature), he will lack the T cells required to induce class switching, and therefore be unable to produce IgE antibodies.

48

When would we observe decreased alpha-fetoprotein, and where is it measured?

Decreased alpha-fetoprotein is an amniotic fluid marker for Down syndrome.

49

Why do we observe recurrent infections in DiGeorge syndrome?

Thymic aplasia. The inability for T cells to mature results in defective cellular immunity and susceptibility to recurrent infections.

50

A 4-month-old boy is brought to the physician by his parents because of twitching of his facial muscles. A review of his records shows that he has previously been seen for several severe episodes of Candida infections. Physical exam shows low-set ears, hypertelorism, and a shortened philtrum. What is the likely diagnosis?

DiGeorge syndrom

51

A 52-yo man with stage II congestive heart failure is treated with high-dose furosemide and loses 15 lb of fluid over several days. A CBC taken before the diuresis shows an RBC count of 5 million/mm3; a CBC taken after diuresis shows an RBC count of 6.5 million/mm3. Which of the following is the most likely explanation for this finding?

(a) increased EPO
(b) polycythemia vera
(c) reactive polycythemia
(d) renal cell carcinoma
(e) cyanotic heart disease

reactive polycythemia

in reactive polycythemia, there is an increase in the Hct/RBC count without a true increase in the number of RBCs secondary to a reduction in plasma volume. This is what happened in this patient as a result of his diuresis.

52

What is secondary absolute polycythemia?

This is an absolute increase in the number of circulating RBCs secondary to increased EPO. This increase in EPO can be appropriate (e.g., due to hypoxia), or inappropriate (e.g., due to ectopic production of EPO, such as in renal cell carcinoma)

53

Relative to normal, what are the RBC count and EPO levels in reactive polycythemia?

Both are normal

54

Relative to normal, what are the RBC count and EPO levels in secondary absolute polycythemia?

Both are increased

55

What is primary absolute polycythemia?

This is also known as Polycythemia Vera.

This is a neoplastic proliferation of mature myeloid cells, particularly RBCs.

56

Relative to normal, what are the RBC count and EPO levels in primary absolute polycythemia?

RBC count is up
EPO levels are down.

The increased numbers of RBCs further suppresses the production of EPO.

57

What mutation is associated with Polycythemia Vera?

Jak2 kinase mutation