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Pediatric Oncology: MDS

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clonal abnormalities associated with MDS
monosomy 7 - most common, no prognostic significance in MDS
trisomy 8 and 21
deletion 5q
chromosomal abnormality more commonly seen in treatment-induced AML over de novo AML
trisomy 8
what is the prognosis of monosomy 7 in AML compared to MDS
no prognostic significance in MDS, but poorer prognosis in AML
what is alkylating agent induced MDS characterized by?
deletions or the loss of a whole chromosome
*latency period 3-5 years*
what is epipodophyllotoxin agent induced MDS characterized by?
translocations involving chromosome band 11q23. Latency period 1-3 years
what constitutional conditions are associated with JMML
NF1
Noonan syndrome
Trisomy 8 mosaicism
what is the renal insufficiency in ALPS due to
glomerulonephritis attributed to immune deposition of antigen-antibody complexes
what are IL-10 levels in ALPS?
elevated
correlate with disease expression
which types of adult MDS have a high incidence of progression of AML?
refractory cytopenia with multilineage dysplasia
refractory anemia with exccess blasts
which types of adult MDS have a low incidence of progression to AML
refractory anemia
refractory anemia with ringed sideroblasts
del 5q: macrocytic anemia
which syndromes have an association with MDS
down, kostman, schwachman diamond, dyskeratosis congenita, blooms, noonans
definition refractory cytopenia
< 2% PB blasts
< 5% marrow blasts
refractory anemia with excess blasts
2-19% PB blasts
5-19% marrow blasts
most frequent translocation in MDS -> AML
AML1/RUNX1
common marrow finding in M7 AML
fibrosis
are GATA-1 mutations seen in TMD or AML
AML
platelet markers
CD 41/42B/61
clinical features of JMML
HSM
LAD
pallor
fever
RASH (can be urticarial)
what is the minimum lab criteria for JMML
no t 9:22
PB monocytosis > 1 x 10 to the 9th/L
BM blasts < 20%
what are additional lab criteria of JMML
need two of the following:
- hgb F increased for age
- myeloid precursors in PB
- clonal abnormality: monosomy 7, t 5;8, trisony 8, monosomy 22
- GM-CSF hypersensitivity of monocyte progenitors in vitro
- autonomouis growth of CD 34 cells
what is the central pathogenesis of JMML
RAS activation
molecular pathogenesis of JMML in Noonan
missense mutation in PTPN11
molecular mutations in JMML
frequent deletions of NF1 (negative regulator of Ras activation)
missense mutation in PTPN11
mutations of KRAS2 and NRAS
% normal cytogenetics in JMML
78
% tranformation to leukemia in JMML
13
criteria for esstential thrombocytosis
platelet count > 600,000
hgb not > 13
normal iron stores
no ph chromosome
no fibrosis of marrow
how common is familial thrombycytosis in pediatric cases of essential thrombocytosis
50%
what platelet morphology is seen in essential thrombocytopenia
hyperlobulated
dysplastic
increased early megas
does familial thrombocytosis have malignant transformation?
no
incidence of what type of disease in family is associated with LCH
thyroid
autoimmune
what cell type is involved in LCH
dendritic cells
how do you diagnose LCH
intracellular birbeck granules that stain with CD207
OR
extracellular staining with CD1a
what type of nuclei are seen with LCH
kidney bean, large cytoplasm
chemo tx for HLH
vp-16, dex, cyclosporine
immunohistochemistry of rosai dorfman
+ S100
+ CD 163
no CD 1a (differentiate from LCH)
what is the MOST common genetic defect in severe hemophilia
inversion 42%
what is the most common genetic defect in mild-moderate hemophilia?
missense 85%
how early can you pre-natally detect Factor 8 deficiency
11-15 weeks by RFLP chorionic villi/amnio

at 18 weeks can check fetal cord blood for F8 levels
in what situations are clinical manifestations of hemophilia seen in women
lyonization of normal x
turner syndrome xo
father with hemophilia/mother carrier
vWD type 2N (normandy)
how can you differentiate a hip bleed from ileopsoas based on physical exam in hemophilia
hip -everted
ileopsoas - inverted
1/2 life factor 8 replacement
factor 9
factor 8 - 12 hours
factor 9 - 20-24 hours
factor dosing replacement
factor 8
factor 9
factor 8 50 U/kg for 100%
factor 9 100U/kg for 100% x 1.3
joint bleeding replacement plan
day 1 80% correction
day 2 40% correction
day 3 40% correction
how does DDAVP work in hemophilia
activation of contact pathway
plasminogen activiation via TPA
release of VWF from endothelial cells
increased platelet adhesion
side effects from DDAVP
hyponatremia
thrombosis
tachyphylaxis
IV dose of DDAVP
0.3 microgram/kg in 30 cc NS over 15 min
dose DDAVP IN
< 50 kg: 150 microgram (1 spray)
>50 kg: 300 microgram (2 sprays)
dose amicar
100mg/kg q 6hr po for 3-7 days
what subclass are F8 inhibitors?
IGG4
does not fix complement
what is a normal F8 inhibitor level
< 0.6 bethesda unit
what does one Bethesda unit equal
amount of inhibitor that inactivates half of the F8 in the incubation unit
what is the residual amount of F8 in the presence of 2 bethesda units inhibitor
25%
which molecular abnormalities are associated with inhibitor development
large deletions (65-85% risk)
nonsense mutations (stop codon)
inversion of intron 22 (21% risk)
what is the incidence of inhibitor development in factor 9 def compared to factor 8
much less
what are the treatment options in hemophilia in the face of inhibitors
activated prothrombin concentrates
recombinent factor 7a
porcine factor 8
immune tolerance
dose of activated prothrombin concentrates when treating in presence of inhibitor
75U/kg
how does recombinent F7a work?
activates factor 9 and factor 10: generate thrombin
dose of porcine Factor 8
50-100U/kg
Under what clinical scenerio can you expect the best response to porcine Factor 8
porcine BU < 15
human BU < 50
side effects of porcine factor 8
allergic reaction
thrombocytopenia
porcine antibody
what determines successful treatment with immune tolerance in hemophilia
BU <0.6
recovery > 66%
half life > 6 hours
immune tolerance treatment strategy in hemophilia
100U/kg/d rF8 until BU< 0.6, recovery >66%, t 1/2 > 6 hours then 100U/kg/d x one month
50U/kg/d x 1 mos
50U/kg/qod x 1 mos
then 20-30 U/kg/tiw x 12 months (this is the prophylactic dose)
what is the definition of a target joint
4 bleeds/joint over 6 months
20 bleeds/joint in a lifetime
where is von willebrand factor stored
endothelial cells and platelets
how does ristocetin induce platelet agglutination?
vWF interaction with platelet receptor Ib/IX
what is the relationship between vWF levels and blood type
lower levels are seen with type O, highest with AB
tests in type 1 vWF
proportionally reduced F8, ristocetin cofactor, and vWF antigen
what is the defect in vWF
functionally and structually normal just less of it
what is the defect in VWF type 2A
absence of large and intermediate sized vWF multimers
what is the defect in vWF type 2B
increased vWF affinity for platelet GP1b and secondary clearance of large sized multimers
platelet count in vWF type 2B
thrombocytopenia
treatment contraindication in vWF type 2B
DDAVP

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