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Heme > Lec 2 Bone Marrow Failure > Flashcards

Lec 2 Bone Marrow Failure Flashcards

1
Q

What is the signature feature of impaired bone marrow production?

A

decreased reticulocyte count

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2
Q

What will bone marrow aspirate show in leukemia or myelodysplastic syndrome?

A

cellular marrow filled with leukemia cells or dysplastic cells of MDS

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3
Q

What will bone marrow biopsy show in aplastic anemia?

A

no hematopoietic cells

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4
Q

What is myelopthisis?

A

bone marrow is infiltrated –> crowding out/impairment of normal hematopoietic cells

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5
Q

What is normal absolute retic count?

A

50,000 to 100,000

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6
Q

What is the definition of anemia?

A

Hgb < 13 in men

Hgb < 12 in women

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7
Q

WHat is the effect of myelopthisis?

A

have crowding of bone marrow –> pancytopenia

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8
Q

What are some things that can infiltrate the bone marrow?

A

metastatic cancer
hematologic malignancies
fibrosis
infection

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9
Q

Should you do bone marrow aspirate or bone marrow biopsy if you suspect myelopthisis?

A

biopsy; infiltrate may cause dry tap if you try to aspirate

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10
Q

What are some characteristic findings in myelopthisis?

A
  • teardrop RBCs in blood

- luekoerythroblastosis = presence of immature WBCs and nucleated RBCs in peripheral blood]

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11
Q

What happens to EPO when you have anemia normally? What about in setting of renal disease?

A

in anemia EPO rises normally to produce more RBCs

in renal disease –> inadequate EPO –> become more anemic

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12
Q

What is general mech of B12 deficiency?

A

have impaired DNA production –> impaired cell turnover since B12 needed for normal DNA synthesis

megaloblastic, macrocytic

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13
Q

What is general mech of folic acid deficiency?

A

have impaired DNA production –> impaired cell turnover since folate is needed for normal DNA synthesis

megaloblastic, macrocytic

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14
Q

What is general mech of iron deficiency?

A

have impaired heme synthesis –> impaired hemoglobin production + anemia

microcytic, hypochromic

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15
Q

What is general mech of anemia of chronic inflammation?

A

iron transport impaired –> iron trapping in macrophages –> unavailable for hemoglobin synthesis

normocytic –> microcytic

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16
Q

What is general mech of sideroblastic anemia?

A

impaired iron utilization –> anemia

microcytic, hypochromic

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17
Q

What is aplastic anemia?

A

bone marrow failure; loss of hematopoietic cells from bone marrow and fatty replacement
–> pancytopenia, severe anemia, leukopenia, thrombocytopenia

normocytic nonhemolytic anemia

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18
Q

What age group[s] get aplastic anemia? Geography?

A
  • peak in early 20s
  • peak again in > 60 yo
  • 2-4x higher incidence in east Asia
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19
Q

What is etiology of aplastic anemia?

A
  • 65% idiopathic; may be immune mediated
  • radiation and drugs
  • virus = infectious
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20
Q

What 2 drugs most commonly associated with aplastic anemia?

A
  • chloramphenicol

- benzene

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21
Q

What are 4 viruses associated with aplastic anemia?

A
  • parvovirus B19
  • EBV
  • HIV
  • HCV
22
Q

What is mech of parvovirus B19 causing aplastic anemia?

A

infects and kills RBC precursors –> pure red cell aplasia

23
Q

What is mech of CMV causing bone failure?

A

affects immunesuppressed pts; CMV infects stromal cells and interferes w/ growth factor production –> pancytopenia

esp seen in post-bone marrow transplant patients

24
Q

What is hepatitis-associated aplastic anemia?

A

occurs after cute non-A; non-B; non-C hepatitis

seen in young males in fare east

likely immune mediated; high mortality

25
Q

How are telomeres associated w/ aplastic anemia?

A

mutation of TERC/TERT genes leading to shortened telomeres b/c non-functional telomerase

seen in 30-50% of patients w/ acquired AA

26
Q

What is the hypothesis of acquired aplastic anemia?

A

due to immune dyregulation of hepatopoiesis from damaged stem cells leading to loss of proliferative capacity or induction of antigens that trigger immune destruction via cytotoxic T cells

27
Q

What is clinical definition of severe aplastic anemia?

A 
bone marrow biopsy cellularity < 25%
AND 2 of the 3:
granulocytes < 500
platelets < 20,000
reticulocytes < 60,000
28
Q

What is clinical definition of very severe aplastic anemia?

A

severe aplastic anemia AND granulocytes < 200

29
Q

What is clinical definition of moderate aplastic anemia?

A

not severe

stable w/ depressed counts > 3 mos

30
Q

What are symptoms of aplastic anemia?

A

fatigue, malaise, pallor, purpura, mucosal bleeding, petechiae, infection

31
Q

How do people w/ aplastic anemia die?

A

usually infection

32
Q

What are possible treatments for aplastic anemia?

A
  • withdrawal offending agent
  • supportive
  • immunosuppression
  • stem cell transplant
  • avoid transfusions in transplant candidates
33
Q

What is the 3 drug immunosuppression medication regimen for aplastic anemia?

A

antithymocyte globulin + cyclosporine + steroids

34
Q

What is treatment for aplastic anemia if refractory to antithymocyte globulin?

A

give eltrombopag = thrombopoietin receptor agonist –> stimulates the few hematopoietic stem cells that are left

35
Q

What is major complication of aplastic anemics treated with immunosuppression?

A

have clonal evolution –> 20% go on to MDS/AML [myelodysplastic syndrome] within 10 years; 10% to PNH [paroxysmal nocturnal hemoglobinuria]

36
Q

What is the most common inherited cause of bone marrow failure?

A

fanconi anemia

37
Q

What is the pathogenesis of fanconi anemia?

A

rare inherited disease causes defect in DNA repair –> increased sensitivity to DNA to physical/chemical damage –> chromosomal breaks

38
Q

What is mech of paroxysmal nocturnal hemoglobinuria?

A

acquired stem cell disease due to defect in synthesis of GPI anchor which anchors DAF/CD55 and CD59 proteins which inhibit complement –> increased complement lysis of RBCs

39
Q

What type of hemolysis in paroxysmal nocturnal hemoglobinuria?

A

intravascular hemolysis

40
Q

What is relationship PNH and aplastic anemia?

A

~ 30% of PNH patients develop aplastic anemia

41
Q

What are some complications of PNH?

A

associated with aplastic anemia; increased risk of thrombosis

42
Q

What is the triad of PNH?

A
  • negative Coobs hemolytic anemia
  • pancytopenia
  • venous thrombosis
43
Q

What is treatment of paroxysmal nocturnal hemoglobinuria?

A

eculizumab

44
Q

What is the mech of eculizumab?

A

monoclonal antibody; prevents conversion C5 –> C5a

thus prevents formation of MAC and interferes with complement lysis of RBCs

45
Q

What do you see on CBC with aplastic anemia?

A
  • low Hb
  • low WBCs
  • low platelets
  • low retic count
  • normal B12/folate
46
Q

What lab tests should you do in patient with aplastic anemia?

A
  • hepatitis screen
  • test for PNH [CD55/CD59]
  • cytogenic studies
  • B12 and folate levels
47
Q

Why do you want to avoid transfusions in pt with aplastic anemia?

A

can lead to alloimmunization from foreign antigens on donor blood –> increase risk of transplant rejection

48
Q

What are the signs/symptoms of fanconi anemia?

A

cafe au lait spots, hyperpigmentation, short stature, infertility

49
Q

What is treatment of fanconi anemia?

A

give androgens

stem cell transplant

50
Q

What are complications of fanconi anemia?

A

increased risk of myelodysplasia, AML, epithelial malignancies

stem cell transplant will cure BM failure but not alter risk for developing other malignancies b/c the defect is seen in ALL cells

Heme (20 decks)

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