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Boards - Step 1 > Pathoma Ch 4,5, 16, 17 (Hemostasis, RBC, Breast, CNS) > Flashcards

Pathoma Ch 4,5, 16, 17 (Hemostasis, RBC, Breast, CNS) Flashcards

4. Hemostasis and Related D/o 5. RBC D/o 16. Breast 17. CNS

1
Q

Distinguish primary and secondary hemostasis

A

Primary hemostasis = formation of weak plt plug
-involves plt, fibrin

Secondary hemostasis = use of coagulation cascade to stabilize plt plug

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2
Q

First thing to happen after BV wall damage

(a) 2 mediators

A

BV wall damage => Immediate reflexive vasoconstriction

a) Mediated by both neural impulse and endothelin (from endothelial cells

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3
Q

Differentiate receptors/factors used for plt adhesion and plt aggregation

A

Steps of primary hemostasis (forming weak plt plug): vasoconstriction, plt adhesion, plt degranulation, finally plt aggregation

Plt aggregation = plts bind to subendothelial collagen by binding to vWF via GP1b receptor

Then plt aggregation for plts to clump together mediated by Gp3a2b receptor using fibrinogen

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4
Q

Name the 2 key molecules released by platelet degranulation in primary hemostasis

A

Plt degranulation (after adhesion, before aggregation) releases

  1. ADP (from plt dense granules) that promotes exposure of Gp2b3a receptors
  2. TXA2 (from plt COX) that stimulates plts aggregation
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5
Q

2 places where vWF is made/released from

A
  1. Weibel-Palade bodies of endothelial cells (main source)
    - this is why ADH (that stimulates Weibel-Palade body release of vWF) is used in the tx of vWD
  2. Alpha-granules of plts
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6
Q

Differentiate the types of bleeding seen in d/o of primary vs. secondary hemostasis

A

Primary hemostasis = formation of weak platelet plug with plts and fibrin
-d/o => mucosal and skin bleeding = epistaxis, hemoptysis, GI bleed, hematuria, petechiae, purpura

Secondary hemostasis = stabilization of plt plug via coagulation cascade
-d/o (coag factor deficiencies) => deep tissue bleeds in joints and muscles, also rebleeding after surgical procedures (classically wisdom teeth)

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7
Q

Differentiate ecchymoses, purpura, and petechiae

A

All skin (superficial) bleeds, differentiated by size
Ecchymoses = superficial bleed over 1cm
Purpura: over 3mm
Petechiae: 1-2mm (indicative of thrombocytopenia

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8
Q

Clinical sign that can help distinguish thrombocytopenia from poor quality of plts

A

Petechiae (1-2mm skin bruises) indicate thrombocytopenia (low number of plts)

-while petechiae are not seen in d/o of plt quality (usually d/o of plt receptors such as Gp1b needed for adhesion, Gp2b3a for aggregation

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9
Q

Bone marrow biopsy expected in ITP

A

Immune thrombocytopenic purpura (IgG against plts)- see megakaryocyte hyperplasia b/c megakaryocytes trying to compensate for low plts

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10
Q

Name 2 general categories of d/o of primary hemostasis

A

D/o primary hemostasis = d/o of plts

  1. Immune thrombocytopenic purpura (ITP) = IgG against plts
  2. Microangiopathic hemolytic anemia (includes HUS and TTP) = pathologic formation of plt microthrombi in small vessels 2/2 either E. Coli O157:H7 or ADAMTS13 deficiency
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11
Q

Differentiate acute and chronic ITP

A

Acute ITP seen in children s/p viral illness or vaccination, get self-limited disease

Chronic form in adults (often women of childbearing age, aka same ppl who get AI d/o)

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12
Q

Plt count and PT/PTT values expected in

(a) ITP
(b) HUS
(c) TTP

A

(a) ITP: reduced plts (2/2 presence of anti-plt IgG so plts destroyed in spleen), PT/PTT normal b/c coagulation cascade (clotting factors) are unaffected
(b) HUS and TTP = microangiopathic hemolytic anemias (meaning pathology of the small HVs that causes hemolytic anemia): reduced plt count (b/c plts used up in microthrombi) and normal PT/PTT

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13
Q

Explain how IVIG aids in the tx of ITP

A

IVIG = intravenous immunoglobulin

Basically give the spleen another immunoglublin to worry about, so it has a decreased capacity to destroy IgG marked plts

-uesd as very acute/transient therapy during symptomatic bleed

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14
Q

Give 2 mechanisms by which splenectomy treats ITP

A

ITP = IgG against antibodies

  1. These antibodies are produced by the spleen
  2. The spleen is where the plts are destroyed once they become bound to the IgGs

So splenectomy removes both the source of the Ab and the site of plt degradation

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15
Q

HUS vs. TTP

(a) Etiology
(b) MC organ system involved

A

HUS and TTP are both microangiopathic hemolytic anemias (pathology of small BVs where plt microthrombi are produced causing hemolytic anemia)

HUS = hemolytic uremic syndrome

(a) Etiology = infection w/ E. Coli 0157:H7
(b) MC involves kidney (umm hence uremic in name)

TTP = thrombotic thrombocytopenic purpura

(a) Etiology = deficiency in ADAMTS13 = enzyme needed to cleave vWF into active form => plts abnormal adhere and form microthrombi
(b) MC see CNS abnormalities (thrombi involving vessels of the CNS)

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16
Q

Name the activating substance of the intrinsic and extrinsic pathways of the coagulation cascade

A

Intrinsic pathway (12 –> 11 –> 9 –> 8 –> X) activates by tissue thromboplastic factor

Extrinsic pathway (7 –> X) activated by subendothelial collagen

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17
Q

Hemophilia A

(a) What is it?
(b) Etiology
(c) Lab findings

A

Hemophilia A

(a) X-linked recessive deficiency in factor VIII (A ‘eight’)
(b) Etiology: usually X-linked recessive but can be 2/2 de novo mutation
(c) Normal bleeding time (b/c primary hemostasis of weak plt plug is normal, normal plt count), prolonged PTT w/ normal PT

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18
Q

Hemophilia A vs. hemophilia B

A

Hemophilia A = deficiency in factor VIII

Hemophilia B = deficiency in factor IX (just one back in the cascade): affects same pathway (intrinsic pathway) => both have the same findings of

  • prolonged PTT, normal PT
  • normal bleeding time b/c plts unaffected
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19
Q

How to differentiate hemophilia A from acquired coagulation factor inhibitor

A

Hemophilia A = deficiency in factor VIII

Acquired (autoimmune usually) inhibition of factor VIII (ex: IgG against factor VIII)

Same clinical and lab findings (deep joint bleeds and prolonged PTT), but different mixing study
-mixing study (mix pt blood w/ normal plasma): PTT corrects in hemophilia A, PTT does NOT correct in acquired inhibitor (b/c there’s an inhibitor present…)

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20
Q

von Willebrand disease: Lab findings

A

von Willebrand disease = deficiency in vWF, factor that binds to subendothelial collagen in damaged endothelium and binds plts via receptor Gp1b

Lab findings: prolonged bleeding time (b/c plt activity is impacted), prolonged PTT b/c factor VIII needs vWF to be stable

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21
Q

Abnormal ristocetin test

A

Ristocetin induces plt agglutination by causing vWF to bind to plt Gp1b (receptor for adhesion).

In vonWillebrand disease, ristocetin won’t cause agglutination (b/c no vWF present) => abnormal test

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22
Q

Explain why the following populations may be deficient in vitamin K

(a) Newborns
(b) Long term abx takers
(c) Malabsorption

A

(a) Newborns have immature gut flora
- hence why nerborns are prophylactically given vitK injection at birth to prevent hemorrhagic disease of newborn
(b) Long term abx kills the gut flora that normal synthesize vitK
(c) Malabsorption of fat-soluble vitamins (ADEK)

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23
Q

Epoxide reductase function

(a) Effect of inhibition

A

Epoxide reductase is the liver enzyme that activates vitamin K

(a) When vitK isn’t active, factors X, IX, VII, II, protein C and S don’t get gamma carboxylated => factors aren’t active

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24
Q

What value is followed to monitor effect of liver failure on coagulation

A

Follow PT: tracks extrinsic pathway (factor VII –> X) and common pathway

  • factor VII produced in the liver, so PT is pretty specific
  • vs. PTT which counts on factors 12, 11, 9, and 8
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25
Q

What is HIT (heparin induced thrombocytopenia)?

A

HIT = development of anti-PF-4 (plt factor 4) in response to plt therapy

So plts get destroyed (prolonged bleeding time) and then plt fragments activate remaining plts and cause thrombosis
-so get both bleeding clotting (uhoh)

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26
Q

Tx for heparin induced thrombocytopenia

A

Tx for HIT (anti-PF4 causing both thrombocytopenia and increased thrombosis)

  1. Stop the heparin!
  2. Add an anticoagulant
    - DONT use coumadin 2/2 icnreased risk of coumadin necrosis
    - first line usually argatroban (direct thrombin inhibitor)
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27
Q

Give some causes of DIC

A

Disseminated intravascular coagulation: always develops 2/2 something else

  • sepsis (especially E. coli or N. meningitidis)
  • obstetric complications 2/2 tissue thromboplastin (activates extrinsic coagulation cascade) in amniotic fluid
  • adenocarcinoma: mucin activates coagulation
  • acute promyelocytic leukemia
  • rattlesnake bit: venom activates coagulation
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28
Q

Explain the physiology of DIC and the following lab results

(a) Plt count
(b) PT/PTT
(c) fibrinogen
(d) Hb

A

DIC = disseminated intravascular coagulation, 2/2 pathologic activation of the coagulation cascade
-then plts consumed => bleeding from skin and mucosal surfaces

(a) Reduced plt count: b/c used up in clots
(b) PT/PTT both elevated b/c coag cascade activated so clotting factors are used up
(c) Fibrinogen decreased b/c used up in clots
(d) Hb reduced b/c intravascular microthrombi causes microangiopathic hemolytic anemia (RBC get sheared in BV as move past clot)

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29
Q

Best screening test for DIC

A

Best screening test for DIC = D-dimer

D-dimer = fibrin degradation product, so elevated means a mature clot is formed and broken down

Key: D-dimer is produced from splitting of fibrin (stable cross linked clot), NOT from splitting of fibrinogen (weak plt plug not yet undergone secondary hemostasis of coagulation cascade)

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30
Q

Tx for DIC

A

DIC- it’s not its own entity, need to address the underlying cause
-sepsis, obstetric complication, adenocarcinoma, APL, rattlestnake venom

In the meantime can give supportive care by transfusion of blood products and cryo

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31
Q

Oral agent for tx of vonWillebrand disease

A

Deficiency in vWF (causing prolonged bleeding time and prolonged PTT) can be tx w/ desmopressin (ADH analogu)

Desmopressin stimulates release of vWF from Weibel-Palade bodies of the endothelial cells

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32
Q

Explain how cirrhosis could disrupt fibrinolysis

A

Liver produced alpha2-antiplasmin (enzyme that inactivates plasmin, recall plasmin breaks up fibrin in clots)

So w/o alpha2-antitripsin, plasmin remains active breaking up clots => presents similar to DIC

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33
Q

Pt presenting w/ apparent DIC (oozing from IV site, very low plt and fibrinogen serum results), but D-dimer is negative

Dx?

A

D-dimer is the best screening test for DIC, if D-dimer not positive pt is not in DIC

D/o of fibrinolysis (ex: no aplha2-antitplasmin needed to inactivate plasmin, so plasmin jsut goes around breaking down clots) will present similar to DIC, but coag cascade is not active so no fibrin => no D-dimer

(b/c recall that D-dimer is not produced by breakdown of fibrinogen which is what the immature clots will be in d/o of fibrinolysis)

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34
Q

Name some of the products produced by the endothelium to protect against thrombus formation

A
  1. Endothelium blocks collagen exposure
  2. Produced PGI1 and NO (NO vasodilates)
  3. Produces tPA to break up clots locally and inactivate coag factors
  4. Produces heparin-like molecules that augment antithrombin III activity
  5. Secretes thrombomodulin which modulates thrombin activity so that thrombin activates protein C instead of converting fibrinogen –> fibrin
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35
Q

Thrombomodulin

(a) Secreted by what?
(b) Fxn

A

Thrombomodulin

(a) Secreted by vascular endothelium
(b) Fxns to change/modulate the fxn of thrombin. So instead of catalyzing fibrinogen–>fibrin (stabilizes clot), thrombin activates protein C (that inactivates factors V and VIII)

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36
Q

Fxn of protein C and S

A

Both protein C and S inactivate coagulation factors V and VIII

(V involved in common pathway, VIII involved in intrinsic pathway)

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37
Q

Explain why pts are kept on heparin while bridging to warfarin/coumadin therapy

A

Protein C/S have a shorter half life than factors 1972 => when first started on coumadin therapy there is a short stage of hypercoagulability where protein C/S are deficient but factors 1972 are still present

So keep pt on heparin for that window period where C/S are inactive and 1972 are active

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38
Q

Describe diagnostic finding of ATIII deficiency

A

Antithrombin III (inactivates thrombin and coagulation factors) increases risk for thrombosis

-especially intravascular b/c ATIII is stimulated/activated by heparin-like molecules produced by endothelium

Diagnostic finding = PTT does not rise in response to heparin
-b/c heparin work by activating ATIII

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39
Q

Antithrombin III

(a) Location of production
(b) Fxn
(c) Key finding of deficiency

A

ATIII

(a) produced in the liver
(b) Inhibits thrombin and coagulation factors
(c) PTT does not rise in response to heparin b/c heparin works by activating/binding to ATIII

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40
Q

Clinical features of amniotic fluid embolus in mother during labor or delivery

A

SOB (embolus to lungs), neurologic symptoms (embolus up to brain), DIC (b/c amniotic fluid has a lot of tissue thromboplastin that activates extrinsic pathway of coag cascade)

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41
Q

Based on the components of hemoglobin, name the 4 causes of microcytic anemia

A

Hb = heme and globin, while heme is iron and protoporphyrin

Reduced iron: (1) iron deficiency anemia (2) anemia of chronic disease
Defective protoporphyrin production (3) sideroblastic anemia
Defective or reduced globin formation (4) thalasesmia

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42
Q

Location of absorption of

(a) Iron
(b) Folate

A

(a) Iron absorbed in the duodenum by DMT1 transporters, then into blood via ferroportin
(b) Folate absorbed in the jejunum

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43
Q

Why is iron always transported bound to something?

A

Transported bound to transferrin, stored as ferritin, always bound b/c of Fenton reaction = ability to produce free radicals that cause peroxidation of membranes and oxidation of proteins/DNA

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44
Q

Differentiate bloodwork seen in early iron deficiency vs. uncompensated chronic iron deficiency

A

Early in iron deficiency anemia there is a normocytic anemia: BM makes normal RBCs just fewer of them. Storage iron gets depleted so ferritin reduces and TIBC increases

Then can no longer compensate and you get microcytic hypochromic anemia: fewer, smaller, lack central pallor

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45
Q

Explain the physiology of anemia of chronic disease

A

Chronic inflammation => chronic elevation in acute phase reactants from liver including hepcidin

Hepcidin sequesters iron away from bacteria, but also prevents us from using our iron stores => despite high ferritin there is low serum iron and low percent saturation

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46
Q

Name 3 causes of acquired sideroblastic anemia

A

MC cause is congenital mutation in ALAS (RLS of protoporphyrin synthesis) but 3 acquired causes

  • vitamin B6 deficiency (cofactor required for ALAS), can see in isoniazid tx
  • alcoholism (mitochondrial poison)
  • Pb poisoning (lead denatures two enzymes used after ALAS in protoporphyrin synthesis)
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47
Q

What type of anemia has an elevated serum iron

A

Serum iron is elevated (above 100) in sideroblastic anemia: b/c iron accessibility isn’t the problem (as it is in iron deficiency or anemia of chrnoic disease), instead there is not enough protoporphyrin for iron to bind to make heme => elevated serum iron and elevated percent saturation

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48
Q

Clinical presentation of 1-4 deletions in alpha globin chain

A

4 alleles for alpha globin

  • 1 deleted = asymptomatic
  • 2 deleted = mild anemia w/ elevated RBC count, cis in Asians vs. trans in Africans
  • 3 deleted = severe anemia, HbH (beta tetramers)
  • 4 deleted = hydrops fetalis lethal in utero, Hb barts (gamma tetramers)
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49
Q

Differentiate cause of alpha and beta thalassemia

A

Alpha thal due to deletions of 2 to 4 of the alpha globin chains, while beta thal is usually due to mutation of the beta globin gene

So deletion vs. mutation

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50
Q

Differentiate Hb electrophoresis seen in beta thal minor and beta thal major

A

Beta thal minor: usually asymptomatic w/ increased RBC count
-Slightly decreased HbA w/ increased HbA2 (5% while normal is 2.5%), and HbF (2% while normal is 1%)

Beta thal major: severe anemia starting a few months after birth
-NO HbA, HbA2 (alpha2delta2) and HbF (alpha2gamma2)

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51
Q

Increased risk of parvovirus aplastic crisis

A
  • Beta thal major
  • Hereditary spherocytosis

Parvovirus B19 infects erythroid precursors, therefore any disease where it’s hard for pt to tolerate temporary halt in erythropoiesis => increased risk of parvovirus aplastic crisis

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52
Q

Name 2 anemias w/ target cells on peripheral smear

A
  • beta thal minor: see target cell ‘bleb’ due to excess membrane
  • Sickle cell: cell continuously sickle and de-sicle thru microcirculation causing reduced cytoplasm => extra membrane causes blebs

Also the two anemias where you get ‘crewcut appearance’ of skull on Xray and ‘chipmunk facies’ due to expansion of hematopoiesis into skull and facial bonesa

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53
Q

Explain how pancreatic insufficiency can cause vit B12 deficiency

A

Pancreas produces enzyme that cleaves R-binder from B12 so that instrinic factor can bind B12 and aid absorption

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54
Q

In a normocytic anemia how can you differentiate peripheral destruction vs. central underproduction

A

Reticulocyte count

Retic under 3% suggests poor marrow response = underproduction

While retic count over 3% suggests good marrow response and peripheral destruction

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55
Q

Describe the breakdown of RBC components

A

Heme –> iron and protoporphyrin

  • iron recycled
  • protoporphyrin –> unconjugated bilirubin

Globin –> amino acid precursors

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56
Q

Hereditary Spherocytosis

(a) Etiology
(b) Explain the shape of RBCs
(c) What causes the anemia?

A

HS

(a) Mutation in RBC cytoskeleton-membrane tethering protein
(b) Loss of RBC membrane renders cell spheroid shape (spherocyte) instead of disc shaped
(c) Its not that fewer cells are produced, but the abnormally shaped cells can’t maneuver the splenic sinusoids => RBCs destroyed by splenic macrophages

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57
Q

What is the osmotic fragilty test used to dx?

A

Osmotic fragilty test- put RBCs in hypotonic solution, normal RBCs have discoid shape that can adapt to a bit of water intake

while spherocytes (seen in hereditary spherocytosis 2/2 defect in RBC cytoskeleton-membrane tethering proteins) have increased fragility in hypotonic solution

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58
Q

Tx for hereditary spherocytosis

A

Tx is splenectomy- if you remove the spleen there is nothing to remove the oddly shaped RBCs => no more anemia

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59
Q

Mutation in SCD

(a) Mutation in HbC

A

SIngle amino acid change replaces normal glutamic acid (hydrophilic) w/ valine (hydrophobic) => beta chain of Hb is defective

(a) Hb C due to autosomal recessive mutation of beta chain where normal glutamic acid is replaced by lysin

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60
Q

Differentiate

(a) HbS
(b) HbA
(c) HbA2
(d) HbF
(e) HbH
(f) Hb barts

A

Hbs

(a) HbS (SCD) = alpha2betaS2
- betaS polymerizes/sickles in hypoxia, acidosis, and dehydration
(b) HbA = adult Hb, alpha2beta2
(c) HbA2 = alpha2delta2
(d) HbF = alpha2gamma2
(e) HbH (seen in alpha thal when 3 of the 4 globin genes are deleted) = beta tetramer
(f) Hb bart (seen in alpha thal when 4 of 4 globin genes are deleted- fetal hydrops) = gamma tetramers

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61
Q

Mechanism of disease in SCD

A

When both beta globin genes are mutated, 90% of Hb is HbS which polymerizes/sickles w/ hypoxia, dehydration, or acidosis

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62
Q

SCD

(a) Common presenting features in infants
(b) MC cause of death in adults

A

(a) Dactylitis in child- b/c of vaso-occlusion (causing infarction) in extremities
(b) MC cause of death in adults = acute chest syndrome 2/2 vaso-occlusion in the pulmonary microcirculation

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63
Q

Differentiate Hb electrophoresis in sickle cell disease vs. sickle cell trait

A

SCD: 90% HbS, 8% HbF (up from normal 1%), 2% HbA2 (normal)
-key here is no HbA (b/c no normal beta globin gene

Sickle cell trait: 55% HbA (higher percent despite equal genes b/c it’s more efficiently made), 43% HbS, 2% HbA2

64
Q

Clinical presentation of sickle cell trait

A

Sickle cell trait is usually asymptomatic b/c RBCs with under 50% HbS don’t sickle, except in the renal medulla

Overtime can lead to medullary microinfarctions => microscopic hematuria and eventually decreased ability to concentrate urine

65
Q

Predominantly intravascular or extravascular hemolysis?

(a) Hereditary spherocytosis
(b) Paroxysmal Nocturnal Hemoglobinuria
(c) SCD
(d) G6PD deficiency
(e) Malaria

A

Hereditary spherocytosis and sickle cell disease are normocytic anemias w/ predominantly extravascular hemolysis

PNH, G6PD deficiency, and malaria are normocytic anemias w/ predominantly intravascular hemolysis

66
Q

Explain pathophysiology of paroxysmal noctural hemoglobinuria

A

PNH: acquired defect in myeloid stem cell (so it’s one line of cells not all cells) causing absent GPI = anchor protein needed for DAF (decay accelerating factor) on surface to protect against complement-mediated damage by inhibiting C3 convertase

No GPI = no DAF = RBC gets damaged by C3 convertase (intravascular hemolysis)

Lysis of RBC, WBC, and plts (b/c all come from the same myeloid stem line!)

67
Q

Paroxysmal noturnal hemoglobinuria

(a) Main cause of death
(b) Increased risk of what malignancy?
(c) Why happens at night

A

PNH

(a) Main cause of death = thrombosis of portal, hepatic, or cerebral veins
- plts destroyed (by complement b/c don’t have GPI to bind DAF to prevent destruction by C3 convertase) release cytoplasmic contents in circulation and induce thrombosis

(b) Increased risk of AML (acute myeloid leukemia) b/c PNH is due to acquired mutation in myeloid stem cell
(c) During sleep breathing becomes shallow => mild respiratory acidosis develops that activates complement

68
Q

Differentiate the African and Mediterranean variant of G6PD deficiency

A

G6PD deficiency = less NADPH to reduce glutathione and protect RBC from oxidative injury from H2O2 => intravascular hemolysis

African variant- G6PD has only mildly reduced t1/2 => mild intravascular hemolysis w/ oxidative stress

Mediterranean variant- G6PD t1/2 is markedly reduced => severe intravascular hemolysis w/ oxidative stress

69
Q

Clinical presentation of G6PD deficiency after sulfa drugs or fava beans

A

Sulfa drugs, fava beans, primaquine, dapsone, infections (things that cause oxidative stress) => intravascular hemolysis of RBCs that presents as hemoglobinuria and back pain (b/c Hb is nephrotoxic) hours after exposure to oxidative stress

70
Q

What is aplastic anemia?

(a) Biopsy finding

A

Damage to hematopoietic stem cell => pancytopenia

(a) Bone marrow biopsy shows empty, fatty marrow

71
Q

Differentiate use of direct vs. indirect Coombs test in diagnosis of autoimmune hemolytic anemia

A

Direct Coomb’s asks if there are immunoglobulins already bound to RBCs

Indirect Coomb’s asks if the pt has anti-RBC antibodies in their serum

72
Q

MC cause of warm agglutinin autoimmune hemolytic anemia

A

MC cause of warm agglutinin (IgG mediated) AI hemolytic anemia = SLE

73
Q

2 infections associated w/ cold agglutinin autoimmune hemolytic anemia

A

IgM binds RBCs and fixes complement in relatively cold temperature of the extremities

Associated w/ mycoplasma pneumoniae and infectious mono

74
Q

Differentiate warm vs. cold agglutinin autoimmune hemolytic anemia

A

Warm agglutinin = IgG binds RBCs in relatively warm temp of central body

Cold agglutinin = IgM binds and fixes complement in relatively cold temperature of the extremities

75
Q

Ideal time to supplement mother to prevent neural tube defects

A

Failure of neural tube to fuse is associated w/ low folate PRIOR to conception

So ideally is best to supplement mother w/ folate before conception

76
Q

Name of d/o when neural tube fails is disrupted

(a) On the cranial plane
(b) On the caudal plane

A

Neural tube defects

(a) Anencephaly = absence of skull and brain 2/2 disruption of cranial end of the neural tube
(b) Spina bifida = failure of posterior vertebral arch to close, disruption at caudal end of the neural tube

77
Q

Differentiate the following

(a) Meningocele
(b) Spina bifida occulta
(c) Meningomyelocele

A

Spectrum of spina bifida

(a) Meningocele = when just meninges protrude thru vertebral defect
(b) Spina bifida occulta = mildest form, presents as a dimple or patch of underlying tissue thru the vertebral defect
(c) Meningomyelocele = both meninges and spinal cord protrude thru vertebral defect

78
Q

Clinical presentation of cerebral aqueduct stenosis

A

Enlarging head circumference 2/2 dilation of lateral ventricles b/c CSF cannot flow from 3rd to 4th ventricle

79
Q

Dandy-Walker Malformation vs. Arnold-Chiari malformation

A

Dandy-Walker malformation = congenital failure of cerebellar vermis to develop => get massive dilation of 4th ventricle

Arnold-Chiari type II = congenital downward displacement of cerebellar vermis and tonsils thru foramen magnum which obstructs CSF flow => hydrocephalus

80
Q

UMN vs. LMN signs

A

UMN signs: hyperreflexia, upgoing (positive) Babinski, spastic paralysis, hypertonia

LMN signs: hyporeflexia, atrophy and weakness, downgoing (negative) Babinski, flaccid paralysis, fasciculations, hypotonia

81
Q

Clinical presentation of poliomyelitis vs. amyotrophic lateral sclerosis

A

Polio- only LMN signs: hyporeflexia, flaccid paralysis w/ atrophy, negative Babinski, fasciculations, hypotonia

While ALS classically presents w/ mix of both LMN and UMN signs

82
Q

How to differentiate ALS from syringomyelia

A

ALS only affects corticostpinal tract (voluntary movement) while syringomyelia has sensory findings (classically loss of pain and temp in cape like distribution)

83
Q

Classic early sign of ALS

A

Atrophy and weakness of hands

84
Q

Explain the mutation involved in familial cases of amyotrophic lateral sclerosis

A

Most cases of ALS are sporadic, but familial cases can be due to zinc-copper superoxide dismutase mutation

Need superoxide dismutase to catalyze O2- –> H2O2, so w/ this mutation pt gets free radical injury to neurons

85
Q

Friedreich ataxia

(a) Mode of inheritance
(b) Mutated gene and its function

A

Friedreich ataxia

(a) Autosomal recessive trinucleotide repeat d/o (GAA repeats) in frataxin gene
(b) Frataxin gene is essential for mitochondrial iron regulation, so loss of frataxin gene => iron buildup => free radical damage of neurons via Fenton rxn

86
Q

Name the 3 spinal tracts and their function

A
  • Spinothalamic tract for pain and temperature sensation
  • lateral corticospinal tract for motor control (voluntary movement)
  • dorsal column for pressure, touch, vibration, and proprioception
87
Q

Spinothalamic tract

(a) Fxn
(b) Location of synapses
(c) Location of decussation

A

Spinothalamic tract

(a) Pain and temperature
(b) Synapse in posterior horn
(c) Second order neuron decussates in anterior white commisure then continues up to thalamus
- 2nd synapse in the thalamus, then continues up to cortex

88
Q

Lateral corticospinal tract

(a) Fxn
(b) Location of synapses
(c) Location of decussation

A

Lateral corticospinal tract

(a) Voluntary movement control
Pyramidal nerves start by (c) decussating in medullary pyramids, then (b) synapse on anterior motor horn of the spinal cord
-2nd order neuron synapse out at the muscle at nmj
Only 2 neurons

89
Q

Dorsal column tract

(a) Fxn
(b) Location of synapses
(c) Location of decussation

A

Dorsal column tract

(a) Vibration, proprioception
(b) Synapses first in inferior medulla, then (c) crosses over in medulla and ascends via medial lemniscus to the thalamus where synapses again then up to cortex

90
Q

What is a syringomyelia?

(a) Associated condition
(b) MC location

A

Syringomyelia = generic term for cyst of cavity within the spinal cord

(a) Associated w/ Arnold-chiari malformations
(b) MC located C8-T1 => causes cape like distribution of loss of pain/temp sensation

91
Q

Clinical presentation of Friedreich ataxia

(a) Associated cardiac condition

A

Freidreich ataxia = autosomal recessive loss of fritaxin gene (mitochondrial protein) causing iron free radical damage that degenerates the cerebellum and spinal cord

Cerebellar degeneration => ataxia
Spinal cord degeneration (multiple tracts) => loss of vibratory sense, proprioception, muscle weakness, loss of DTRs
Presents in early childhood, wheelchair bound in a few years

(a) Hypertrophic cardiomyopathy

92
Q

Which layers of the meninges are involved in meningitis

A

Only the pia and arachnoid (not the dura) make up the leptomeninges which are involved in meningitis

-dura matter is “dura-ble”

93
Q

MC infectious agent causing meningitis by age group

(a) Neonates
(b) Children and teenagers
(c) Adults and elderly

A

Meningitis by age groups

(a) Neonates = GBS, E. coli, and listeria monocytogenes
- GBS and E. Coli thru vaginal canal

(b) Children and teenagers = N. meningitidis
(c) Adults and elderly = Strep pneumo

94
Q

Classic organism responsible for meningitis in unvaccinated child

A

H. influenza in nonvaccinated infants

95
Q

Pathway that neisseria meningitides takes to get to the brain

A

N. meningitides enters thru the nasopharynx, then into the blood stream to hematgenously spread to the leptomeninges

96
Q

Lumbar puncture

(a) Performed at what vertebral level
(b) Poke thru what layers?

A

LP

(a) Ideally btwn L4-L5 (at the level of the iliac crest)
(b) Poke thru skin, epidural space, dura, arachnoid to get into subarachnoid space
- doesn’t poke thru pia!!!

97
Q

CSF findings that differentiate

(a) Bacterial and viral meningitis
(b) Viral and fungal meningitis

A

LP findings

(a) Bacterial meningitis- neutrophilia w/ reduced CSF glucose (then can use gram stain and culture to identify organism)
- Viral meningitis = leukocytes elevated and normal CSF glucose (viruses are debatedly not alive, they don’t consume glucose!)

(b) Both viral and fungal meningitis have elevated lymphocytes in CSF, but viral will have normal glucose while fungal will have reduced glucose

98
Q

Normal CSF glucose

A

Normal CSF glucose = 2/3 (serum glucose)

So if serum glucose is 100, expect CSF glucose in mid 60s

99
Q

Differentiate etiology of pale vs. hemorrhagic cerebral infarct

A

Pale cerebral infarct from thrombotic disease (ex: atherosclerosis) b/c atherosclerotic plaque can’t be degraded => blood doesn’t return to area

Hemorrhagic infarct from embolic disease (ex: AFib to MCA), clot lysed and blood re-enters so area becomes hemorrhagic

100
Q

Etiology of lacunar strokes

(a) Explain why deep brain structures are the MC affected

A

Lacunar strokes: chronic HTN causes hyaline arteriolosclerosis of cerebral vessels which narrows vessels

(a) MC affects deep brain structures b/c it’s the small perforating branches off the MCA (lenticulostriate vessels) that are smallest and easily narrow

101
Q

Involvement of what location leads to

(a) Pure motor stroke
(b) Pure sensory stroke

A

(a) Pure motor stroke 2/2 lacunar stroke of internal capsule

(b) Pure sensory stroke 2/2 lacunar stroke of thalamus

102
Q

Explain how chronic HTN increases risk of intracerebral hemorrhage

A

Chronic HTN => hyaline arteriolosclerosis that can narrow vessels (cause lacunar stroke) but also can weaken vessel wall, forming Charcot-Bouchard microaneurysms of the lenticulostriate vessels (perforating branches off MCA)

103
Q

Subarachnoid hemorrhage

(a) LP finding
(b) MC cause

A

SAH

(a) Xanthochromia (yellow hue of CSF 2/2 bilirubin) due to blood in the subarachnoid space
(b) MC cause = berry aneurysm

104
Q

MC location of SAH

(a) Why

A

MC location = branching points of the anterior communicating artery (anterior circle of Willis)

(a) B/c at these branch points the media fails to develop = weaker wall => wall balloons out
- berry aneurysm = thin-walled saccular outpouchings that lack media layer

105
Q

Epidural vs. subdural hematoma

(a) Etiology
(b) Shape on CT
(c) Clinical presentation

A

Epidural hematoma

(a) 2/2 skull fracture injuring middle meningeal artery
(a) Lens shape on CT
(b) Can present w/ lucid interval before blood accumulates

Subdural hematoma

(a) From rupture of bridging veins
(b) Crescent shaped on CT
(c) Progressive neurologic signs

106
Q

Complication of tonsillar herniation vs. subfalcine herniation

A

Tonsillar herniation = cerebellar tonsil thru foramen magnum. Compression of brain stem => cardiopulmonary arrest

Subfalcine herniation = cingulate gyrus displaced under falx cerebri. Causes compression of anterior cerebral artery => infarction

107
Q

3 consequences of uncal herniation

A

Uncus lobe of the temporal lobe herniates under the tentorium cerebelli

  1. Compression of CN III => eyes ‘down and out’ w/ dilated pupil
  2. Compression of posterior cerebral artery => occipital lobe infarction => contralateral homonymous hemianopsia
  3. Rupture of paramedian artery => Duret (brainstem) hemorrhage
108
Q

What are leukodystrophies?

A

Leukodystrophy = d/o of the white matter (aka myelinated tissue) due to mutation in enzymes necessary for production or maintenance of myelin

109
Q

MC leukodystrophy

A

MC leukodystrophy (aka mutation cuasing defective production or maintenance of myelin) = metachromatic leukodystrophy

= lysosomal storage disease b/c sulfatides cannot be degraded so they accumulate in the lysosomes of oligodendocytes

110
Q

Subacute sclerosing panencephalitis

(a) Part of brain affected
(b) Etiology

A

Subacute sclerosing panencephalitis

(a) Both white and gray matter (hence ‘pan’ encephalitis)
(b) Etiology = measles virus
- persistent brain infection by measles virus, infection in infancy then neurologic signs arise in childhood

111
Q

Progressive multifocal leukoencephalopathy

(a) Etiology
(b) Clinical presentation

A

PML

(a) Reactivation of the JC virus
- usually due to immunosuppression allowing for reactivation
(b) Rapidly progressive neurologic signs leading to death

112
Q

Central pontine myelinolysis

(a) Physiology
(b) Etiology
(c) Clinical presentation

A

CPM

(a) Focal demyelination (destruction of the white matter) of the pons
(b) Too rapid correction of hyponatremia, usually in the severe malnourished
- give Na+ which draws water out of the brain
(c) Acute b/l paralysis- “locked in” syndrome- paralyzed except for eyes

113
Q

Distinguish degenerative d/o of cortex vs. basal ganglia

A

Degeneration of cortex => dementia

  • Alzheimers
  • Lewy Body dementia

While degeneration of the basal ganglia (deeper structures) => movement d/o

  • Parkinsons
  • Huntingtons
114
Q

2 MC cause of dementia

A

Dementia defined as memory loss w/ cognitive dysfunction w/o LOC

1st MC = Alzheimers
2nd MC = Vascular dementia

115
Q

Allele associated w/

(a) Increased
(b) Decreased

risk of Alzheimers

A

(a) ApoE4 allele increases risk for Alzheimers- b/c E4 allele increased breakdown of amyloid precursor protein into Abeta protein (that can’t be excreted and therefore gets deposited)

(b) ApoE2 (lower number) allele conveys lower risk of Alzheimers
- ApoE2 allele is protective

116
Q

Explain why Down syndrome is a model of early onset Alzheimers

A

Downs = 3 copies of chrom 21, chrom 21 contains amyloid precursor protein (APP), which gets broken down into Abeta protein that can’t be excreted => deposits in tissues and causes Alzheimers

So pts w/ an extra copy of APP allele make extra APP => more Abeta protein to accumulate

117
Q

Two dementia d/o w/ tau deposits and how to distinguish them

A

Tau = microtubule-associated protein

Neurofibrillary tangles = intracellular aggregates of fibers composed of hyperphosphorylated tau protein seen in Alzheimer

While round aggregates of tau protein deposit in the cortex neurons in Pick disease (frontotemporal dementia)

118
Q

List the TRAP mneumonic for the clinical features of Parkinson disease

A

Clinical features of Parkinson disease

Tremor- pill rolling tremor at rest
Rigidity- cogwheel rigidity of extremities
Akinesia/bradykinesia- slowing of voluntary movement, expressionless face
Postural instability and shuffling gait

119
Q

Parkinson disease vs. Lewy-body dementia

(a) Clinical distinguish
(b) Histologic finding

A

Parkinson disease

(a) Starts w/ movement features, dementia comes later
(b) Histologically: lewy bodies (round, eosinophilic inclusions of alpha-synuclein) in the substantia nigra of the basal ganglia

Lewy-body dementia

(a) Early onset dementia w/ movement features next or simultaneously (key is that dementia is not delayed)
(b) Lewy bodies (round, eosinophilic inclusions of alpha-synuclein) in the cortex

Recall overall principle:

  • cortical degeneration => dementia
  • basal ganglia degeneration => movement d/o
120
Q

2 diseases that contain Lewy bodies

A
  1. Parkinson disease: Lewy bodies (round eosinophilic inclusions) in the deep nuclei of the substantia nigra
  2. Lewy Body dementia: Lewy bodies in the cortex (peripherally)
121
Q

Explain where anticipation of Huntington disease occurs

A

Further trinucleotide expansion occurs in spermatogenesis, increasing repeats = anticipation

122
Q

Huntington disease

(a) Average age of presentation
(b) Differentiate chorea and athetosis

A

Huntington disease

(a) 40 yoa
(b) Chorea = rapid involuntary contractions, while athetosis are slow involuntary snake-like movements of fingers

123
Q

Explain the physiology of Huntington disease

(a) Degeneration of what neurons?
(b) Mode of inheritance
(c) Location of mutated gene

A

Huntingtons: loss of GABAergic inhibition on the cortex => get random uncontrolled neuronal firing

(a) Degeneration of GABAergic neurons in the caudate nucleus of the basal ganglia
(b) Aut dom of CAG trinucleotide repeats
(c) Huntington gene on chromosome 4

124
Q

Explain the physiology of spongiform encephalopathy

(a) Configuration of prion proteins

A

Spongiform encephalopathy- prior proteins are usually in alpha-helical configuration

(a) Can convert to beta-pleated conformation (not degradable) sporadically, inherited, or transmitted (exposure to human infected tissue)
- vicious cycle b/c beta-pleated conformation (pathologic protein) converts normal protein into more pathologic form

125
Q

CNS tumor: what percent are mets vs. primary?

(a) Typical location of metastatic tumors

A

50% of CNS tumors are mets, while 50% are primary (so 50/50 shot!)

(a) Mets: multiple, well-circumscribed lesions at the gray-white jxn
MC = lung, breast, kidney

126
Q

Differentiate the fxn of these CNS cells

(a) Astrocytes
(b) Meningothelial cells
(c) Ependymal cells
(d) Oligodendrocytes

A

CNS cell in addition to neurons

(a) Astrocytes form BBBB
(b) Meningothelial cells form the meninges
(c) Ependymal cells line the ventricles
(d) Oligodendrocytes myelinate CNS neurons

127
Q

Differentiate location of CNS tumors in adults vs. children

A

Adult- most CNS tumors are supratentorial, while in children primary CNS tumors are usually infratentorial

128
Q

CNS tumors of the following cells occur in children or adults?

(a) Astrocytes
(b) Oligodendrocytes
(c) Ependymal cells
(d) Meningothelial cells

A

(a) Astrocyte tumors
- malignant glioblastoma multiform (GBM) in adults
- benign pilocytic astrocytoma in children

(b) Oligodendrocytes
- malignant oligodendroglioma in adults

(c) Ependymal cells
- malignant ependymoma in children

(d) Meningiothelial cells
- meningioma in adults

129
Q

MC primary CNS tumor

(a) malignant in adults
(b) benign in adults
(c) benign in children

A

MC primary CNS tumor

(a) MC primary malignant CNS tumor in adults = GBM (glioblastoma multiforme) of astrocytes
(b) MC primary benign CNS tumor in adults = meningioma
(c) MC primary benign CNS tumor in children = pilocytic astrocytoma from astrocytes

130
Q

Glioblastoma multiforme

(a) Cell of origin
(b) Classic gross pathology finding
(c) Histologic stain
(d) Prognosis

A

MC primary CNS tumor in adults = GBM

(a) Arises from astrocytes, high-grade malignant tumor of astocytes = GBM
(b) Butterfly lesion
(c) Tumor cells are GFAP positive
- GFAP is the intermediate filament in glial cells
(d) Poor prognosis

131
Q

Meningioma

(a) RF
(b) Classic clinical presentation
(c) Attached to what layer?

A

Meningioma

(a) RF: female!! Tumor expresses estrogen receptor
(b) Seizures b/c tumor compresses (w/o invading) the cortex
(c) Tumor as a round mass attached to the dura

132
Q

Intracerebral tumor removed and tumor cells stain S-100 positive

Dx?

A

S-100 positive cells = cells derived from the neural crest, MC Schwann cells (won’t find melanocytes in the head)

Dx = Schwannoma = benign tumor of schwann cells

133
Q

Oligodendroglioma

(a) Benign?
(b) Imaging
(c) MC location

A

Oligodendroglioma

(a) Malignant tumor of the oligodendrocytes (cells that myelinate CNS neurons)
(b) On imaging: calcified tumor in the white matter
(c) Usually involving the frontal lobe

134
Q

GFAP positive tumor cells ddx

A

GFAP is the intermediate filament used in glial cells, esp astrocytes => tumor cells of glioblastoma multiforme (malignant high grade tumor of astrocytomas) and pilocytic astrocytoma (benign tumor of astrocytes) are both GFAP positive

135
Q

Primary CNS tumor in children w/ the worse prognosis

A

Medulloblastoma = malignant tumor derived from neuroectoderm

136
Q

Medulloblastoma

(a) Cells of origin
(b) Histologic finding
(c) Explain drop metastasis

A

Medulloblastoma

(a) Arises from neuroectoderm (granular cells of the cerebellum)
(b) Histology: small round blue cells
(c) Drop metastasis = mets to the cauda equina

137
Q

Craniopharyngioma

(a) Cells of origin
(b) Classic clinical presentation
(c) Imaging finding

A

Craniopharyngioma
(pharynx in name b/c arises from Rathke’s pouch which is from the floor of the mouth or pharynx)

(a) Rathke’s pouch (give rise to anterior pituitary, part of the surface ectoderm)
(b) Bitemporal hemianopsia 2/2 mass effect in the sella turcica on optic chiasm just above
(c) Calcified tumor in sella turcica
(remember calcified b/c derived from mouth, or ‘tooth-like’ tissue)

138
Q

MC clinical presentation of ependymoma

A

Ependymoma = malignant tumor of ependymal cells (line ventricular space), seen in children

MC arise in the 4th ventricle and obstruct CSF flow => p/w hydrocephalus

139
Q

2 non-cancerous causes of calcification on mammography

A
  1. fat necrosis- get saponification

2. sclerosing adenosis in fibrocystic change

140
Q

Distinguish the two layers of epithelium that line lobules and ducts of breast tissue

A

2 layers: both which line the lobules and ducts of breast tissue

Inner luminal cell layer- produces milk

Outer myoepithelial layer- contracts to propel milk towards the nipple

141
Q

Why is breast cancer MC found in the upper outer quadrant

A

B/c lobules and ducts (functional units of the breast) are present at highest density in the upper outer quadrant

Highest density of tissue = more tissue to become cancerous

142
Q

Name fibrocystic-related changes of the breast that do increase risk for invasive carcinoma

A

Atypical hyperplasia- 5x increased risk

Ductal hyperplasia and sclerosing adenosis- 2x increased risk

Butttttt apocrine metaplasia doesn’t infer increased risk!

143
Q

Differentiate intraductal papilloma and papillary carcnioma

A 
Intraductal papilloma (benign papillary growth): fibrovascular changes that maintains the two standard epithelial layers (both luminal and myoepithelial)
-seen in younger F

While papillary carcinoma (malignant) has fibrovascular projections that are lined by epithelial (luminal) cells W/O myoep cells
-risk increases w/ age

Both present w/ bloody nipple discharge

144
Q

Clinical presentation of intraductal papilloma

A

Intraductal papilloma = benign fibrovascular growth that maintains the two standard epithelial layers of lining presents w/ bloody nipple discharge

Its malignant counterpart (papillary carcinoma) also p/w bloody nipple discharge

145
Q

What is a fibroadenoma?

A

Fibroadenoma = MC tumor in pre-menopausal F

-benign breast tumor of both fibrous tissue and glands

146
Q

Differentiate fibroadenoma and Phyllodes tumor

A

Fibroadenoma = benign breast mass of both fibrous and glandular tissue

While Phyllodes tumor has an overgrowth of the fibrous component
-MC in postmenopausal and can be malignant

147
Q

How are the following most commonly detected

(a) DCIS
(b) Large vs. small IDC
(c) LCIS

A

(a) DCIS often detected as calcification on mammography, doesn’t usually produce a mass

(b) IDC over 2cm detected by palpation of mass, IDC btwn 1-2cm detected by mammography
(c) LCIS usually discovered incidentally on biopsy (biopsy for something else and find LCIS) b/c it doesn’t produce a mass or calcification

148
Q

Differentiate DCIS and IDC

A

Both are malignant cells, difference is if invaded basement membrane

DCIS = malignant prolif of cells in ducts w/o invasion of BM

149
Q

What type of cancer is Paget’s disease of the breast?

(a) Clinical presentation
(b) Clinical relevance

A

Paget’s disease of the breast = DCIS that extends up to the ducts to involve the skin of the nipple

(a) Nipple ulceration and erythema
(b) Almost always associated w/ underlying carcinoma
- while extramammary paget’s is not associated w/ underlying carcinoma

150
Q

Briefly describe differentiating features of the 4 subtypes of invasive ductal carcinoma

(a) Tubular carcinoma
(b) Mucinous carcinoma
(c) Medullary carcinoma
(d) Inflammatory carcinoma

A

Invasive ductal carcinoma

(a) Tubular- tubules lacking myoepithelial cells
(b) Mucinous- abundant extracellular mucin “tumor cells floating in mucus pool”
(c) BRCA1 carriers, high grade malignant cells in inflammatory background (lymphocytes and plasma cells)
(d) Inflammatory- can be mistaken for acute mastitis b/c presents as inflamed, swollen breast b/c cancer is in the dermal lymphatics (lymphatic drainage is blocked)

151
Q

MC type of invasive breast cancer

A

80% of invasive carcinomas of the breast are IDC (invasive ductal carcinoma), so much more common than ILC (invasive lobular carcinoma)

152
Q

Tx of LCIS

A

LCIS often tx w/ tamoxifen and close f/u

-tamoxifen decreases growth response to hormones and decreases the already low risk of progression to invasive carcinoma

153
Q

Explain the histological finding of invasive lobular carcinoma

A

ILC- cells characteristically grow in single-file pattern b/c they lack E-cadherin that keeps them stuck together

-the key here is that these cells don’t form ducts (therefore are in the lobules) b/c they lack E-cadherin adhesion protein

154
Q

Cancers associated w/

(a) BRCA1
(b) BRCA2

A

(a) BRCA1 = breast cancer (esp medullary subtype of invasive ductal carcinoma) and ovarian carcinoma (classically serous carcinoma)
(b) BRCA2 associated w/ breast carcinoma in males

155
Q

In males what type of breast cancer develops?

(a) Location

A

Males don’t develop lobules (don’t make milk…) so they develop invasive ductal carcinoma

(a) Subareolar mass b/c the highest density of breast tissue in males is under the nipple

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