Hema/Onco

Question 1

Treatment for ABO type of erythroblastosis fetalis

Answer 1

Phototherapy or exchange transfusion
———
Fetal erythropoiesis occurs in: Yolk sac (3–8 weeks), Liver (6 weeks–birth), Spleen (10–28 weeks), Bone marrow (18 weeks to adult)

Embryonic globins: ζ and ε
Fetal hemoglobin (HbF) = α2 γ2
Adult hemoglobin (HbA1 ) = α2 β2

HbF has higher affinity for O2 due to less avid binding of 2,3-BPG, allowing HbF to extract O2 from maternal hemoglobin (HbA1 and HbA2) across the placenta
HbA2 (α2δ2): form of adult Hgb present in small amounts
———
Hemolytic disease of the fetus and newborn: also known as erythroblastosis fetalis

Rh hemolytic disease: Rh⊝ pregnant patient with Rh⊕ fetus
MOA: first pregnancy: patient exposed to fetal blood (often during delivery) -> formation of maternal anti-D IgG
Subsequent pregnancies: anti-D IgG crosses placenta ->attacks fetal and newborn RBCs -> hemolysis
Presentation: Hydrops fetalis, jaundice shortly after birth, kernicterus
Prevention: administration of anti-D IgG to Rh⊝ pregnant patients during third trimester and early postpartum period (if fetus Rh⊕); prevents maternal anti-D IgG production

ABO hemolytic disease: type O pregnant patient with type A or B fetus
Preexisting pregnant patient anti-A and/or anti-B IgG antibodies cross the placenta -> attack fetal and newborn RBCs -> hemolysis
Presentation: mild jaundice in the neonate within 24 hours of birth Unlike Rh hemolytic disease, can occur in firstborn babies and is usually less severe
Tx: phototherapy or exchange transfusion

Question 2

Term used when neutrophil precursors (eg, band cells, metamyelocytes) are present in peripheral blood

Answer 2

Left shift
———
Hematopoeisis: multipotent stem cell becomes either myeloid cell or lymphoid cell

Myeloid: can become erythroblast, megakaryoblast, myeloblast and monoblast
Erythroblast -> reticulocyte -> erythrocyte
Megakaryoblast -> megakaryocyte -> platelets
Myeloblast can become eosinophil, basophil, or band cell -> neutrophil
Monoblast -> monocyte -> macrophage

Lymphoid: can become NK cell, B-cell -> plasma cell, and T cell which can become either helper or cytotoxic T cell
———
Neutrophils: acute inflammatory response cells; phagocytic. Multilobed nucleus
Specific granules contain leukocyte alkaline phosphatase (LAP), collagenase, lysozyme, and lactoferrin
Azurophilic granules (lysosomes) contain proteinases, acid phosphatase, myeloperoxidase, and β-glucuronidase
Inflammatory states (eg, bacterial infection): neutrophilia and changes in neutrophil morphology, such as left shift, toxic granulation (dark blue, coarse granules), Döhle bodies (light blue, peripheral inclusions), and cytoplasmic vacuoles

Neutrophil chemotactic agents: C5a, IL-8, LTB4 , 5-HETE (leukotriene precursor), kallikrein, platelet-activating factor, N-formylmethionine (bacterial proteins)

Hypersegmented neutrophils (nucleus has 6+ lobes): vitamin B12 /folate deficiency.

Left shift: reflects states of myeloid proliferation (eg,inflammation, CML)

Leukoerythroblastic reaction: left shift accompanied by immature RBCs
Suggests bone marrow infiltration (eg, myelofibrosis, metastasis)

Question 3

Septic shock is initiated by lipid A from bacterial lipopolysaccarides binding to what component of macrophages?

Answer 3

CD14
———
Erythrocytes: carry O2 to tissues and CO2 to lungs
Anucleate and lack organelles; biconcave, with large surface area-to-volume ratio for rapid gas exchange
Life span: ~120 days in healthy adults; 60-90 days in neonates. Source of energy: glucose (90% used in glycolysis, 10% used in HMP shunt)
Membranes contain Cl−/HCO3 antiporter, which allow RBCs to export HCO3 and transport CO2 from the periphery to the lungs for elimination

Erythrocytosis = polycythemia
Anisocytosis = varying sizes
Poikilocytosis = varying shapes

Reticulocyte = immature RBC; reflects erythroid proliferation

Bluish color (polychromasia) on Wright-Giemsa stain of reticulocytes represents residual ribosomal RNA
———
Thrombocytes: involved in 1° hemostasis
Anucleate small cytoplasmic fragments derived from megakaryocytes
Life span: 8–10 days
Endothelial injury -> aggregate with other platelets and interact with fibrinogen to form platelet plug
Contain dense granules (Ca2+, ADP, Serotonin, Histamine) and α granules (vWF, fibrinogen, fibronectin, platelet factor 4)
Approximately 1⁄3 of platelet pool is stored in the spleen

vWF receptor: GpIb
Fibrinogen receptor: GpIIb/IIIa
Thrombopoietin stimulates megakaryocyte proliferation
Alfa granules contain vWF, fibrinogen, fibronectin, platelet factor four
———
Monocytes: found in blood, differentiate into macrophages in tissues
Single, large, kidney-shaped nucleus
Extensive “frosted glass” cytoplasm
———
Macrophages: phagocytose bacteria, cellular debris, and senescent RBCs
Long life in tissues
Activated by γ-interferon
Canfunction as antigen-presenting cell via MHC II
Important cellular component of granulomas (eg, TB, sarcoidosis), where they may fuse to form giant cells

Macrophage naming varies by specific tissue type (eg, Kupffer cells in liver, histiocytes in connective tissue, Langerhans cells in skin, osteoclasts in bone, microglial cells in brain)

Question 4

Basophilia is uncommon but can be sign of what?

Answer 4

Myeloproliferative disorders, particularly CML
———
Eosinophils: defend against helminthic infections (major basic protein)
Bilobate nucleus
Packed with large eosinophilic granules of uniform size
Highly phagocytic for antigen-antibody complexes
Produce histaminase, major basic protein (MBP, a helminthotoxin), eosinophil peroxidase, eosinophil cationic protein, and eosinophil-derived neurotoxin

Causes of eosinophilia: Parasites, Asthma, Chronic adrenal insufficiency, Myeloproliferative disorders, Allergic processes, Neoplasia (eg, Hodgkin lymphoma), Eosinophilic granulomatosis with polyangiitis
———
Basophils: mediate allergic reaction
Densely basophilic granules contain heparin (anticoagulant) and histamine (vasodilator)
Leukotrienes synthesized and released on demand
———
Mast cells: mediate local tissue allergic reactions
Contain basophilic granules
Originate from same precursor as basophils but are not the same cell type
Can bind Fc portion of IgE to membrane
Activated by tissue trauma, C3a and C5a, surface IgE cross-linking by antigen (IgE receptor aggregation) -> degranulation -> release of histamine, heparin, tryptase, and eosinophil chemotactic factors

Involved in type I hypersensitivity reactions
Cromolyn sodium prevents mast cell degranulation (used for asthma prophylaxis)
Vancomycin, opioids, and radiocontrast dye can elicit IgE-independent mast cell degranulation

Mastocytosis: rare; proliferation of mast cells in skin and/or extracutaneous organs
Associated with c-KIT mutations and increased serum tryptase
Increased histamine -> flushing, pruritus, hypotension, abdominal pain, diarrhea, peptic ulcer disease
———
Dendritic cells: highly phagocytic antigen-presenting cells (APCs)
Function as link between innate and adaptive immune systems
Express MHC class II and Fc receptors on surface
Can present exogenous antigens on MHC class I (cross-presentation)

Question 5

Cells with “clock-face” chromatin distribution and eccentric nucleus, abundant RER, and well-developed Golgi apparatus

Answer 5

Plasma cells
———
Lymphocytes: round, densely staining nucleus with small amount of pale cytoplasm

NK cells: innate immunity (especially intracellular pathogens)
Larger than B and T cells
Distinctive cytoplasmic lytic granules (containing perforin and granzymes) -> when released, act on target cells to induce apoptosis
Distinguish between healthy and infected cells by identifying cell surface proteins (induced by stress, malignant transformation, or microbial infections)
——
B cells: humoral immune response
Originate from stem cells in bone marrow and matures in marrow
Migrate to peripheral lymphoid tissue (follicles of lymph nodes, white pulp of spleen, unencapsulated lymphoid tissue)
When antigen is encountered, B cells differentiate into plasma cells (which produce antibodies) and memory cells
Can function as an APC
——
T cells: cellular immune response
Originate from stem cells in the bone marrow, but mature in the thymus
Differentiate into cytotoxic Tcells (express CD8, recognize MHC I), helper T cells (express CD4, recognize MHC II), and regulatory T cells
CD28 (costimulatory signal) necessary for T-cell activation
Most circulating lymphocytes are T cells (80%)
CD4 helper T cells: primary target of HIV
——
Plasma cells: produce large amounts of antibody specific to a particular antigen
“Clock-face” chromatin distribution and eccentric nucleus, abundant RER, and well-developed Golgi apparatus
Found in bone marrow and normally do not circulate in peripheral blood

Multiple myeloma: plasma cell dyscrasia

Question 6

Test used for pre transfusion blood type testing

Answer 6

Indirect Coombs
———
Hgb electrophoresis: on a gel, hemoglobin migrates from the negatively charged cathode to the positively charged anode
HbA migrates the farthest, followed by HbF, HbS, and HbC
Missense mutations in HbS and HbC replace glutamic acid ⊝ with valine (neutral) and lysine ⊕, respectively, making HbC and HbS more positively charged than HbA
———
Coomb’s test: also called antiglobulin test
Detects the presence of antibodies against circulating RBCs
Direct Coombs test: anti-Ig antibody (Coombs reagent) added to patient’s RBCs; RBCs agglutinate if RBCs are coated with Ig
Used for AIHA diagnosis

Indirect Coombs test: normal RBCs added to patient’s serum
If serum has anti-RBC surface Ig, RBCs agglutinate when Coombs reagent is added
Used for pretransfusion testing

Question 7

True or false: Platelets bind vWF via GpIb receptor at the site of injury ONLY

Answer 7

True
———
Platelet plug formation (primary hemostasis)
1) endothelial damage -> transient vasoconstriction via neural stimulation reflex and endothelin released from damaged cell

2) vWF binds to exposed collagen; vWF is from Weibel-Palade bodies of endothelial cells and α-granules of platelets

3) platelets bind vWF via GpIb receptor at the site of injury only (specific) → platelets undergo conformational change → Platelets release ADP and Ca2+ (necessary for coagulation cascade), TXA2 → ADP helps platelets adhere to endothelium

4a) ADP binding to P2Y12 421 receptor induces GpIIb/IIIa expression at platelet surface

4b) Fibrinogen binds GpIIb/IIIa receptors and links platelets
Pro-aggregation factors: TXA2 (released by platelets),↓blood flow,↑platelet aggregation Balance between Anti-aggregation factors: PGI2 and NO (released by endothelial cells),↑blood flow,↓ platelet aggregation
→ Temporary plug stops bleeding; unstable, easily dislodged → coagulation cascade (secondary hemostasis)
———
Thrombogenesis: formation of insoluble fibrin mesh
Aspirin irreversibly inhibits cyclooxygenase, thereby inhibiting TXA2 synthesis
Clopidogrel, prasugrel, ticagrelor, and ticlopidine inhibit ADP-induced expression of GpIIb/IIIa by blocking P2Y12 receptor
Abciximab, eptifibatide, and tirofiban inhibit GpIIb/IIIa directly
Ristocetin activates vWF to bind GpIb; failure of aggregation with ristocetin assay occurs in von Willebrand disease and Bernard-Soulier syndrome
Desmopressin promotes the release of vWF and factor VIII from endothelial cells
———
Coagulation and kinin pathways: pg 445

Hemophilia A: deficiency of factor VIII (XR)
Hemophilia B: deficiency of factor IX (XR)
Hemophilia C: deficiency of factor XI (AR)

Kallikrein activates bradykinin ACE inactivates bradykinin

Question 8

Warfarin inhibits this enzyme, thereby slowing down clotting factor synthesis

Answer 8

Vitamin K epoxide reductase
———
Vitamin K dependent coagulation:

Oxidized (inactive) vit K is converted to reduced (active) vitamin K by epoxide reductase

Vit K dependent gamma-glutamyl carboyxylase uses the vit K reduction reaction to activate II, VII, IX, X (clotting factors), C and S (anticoagulants)

Factor VII: shortest half life
Factor II: longest half-life

Clotting factors and thrombon catalyze conversion of fibrinogen to fibrin

Neonates lack enteric bacteria, which produce vit K -> early administration of vit K overcomes neonatal deficiency/coagulopathy
———
Vitamin K deficiency: decreased synthesis of clotting factors and proteins C and S

Warfarin inhibits vitamin K epoxide reductase, delaying clotting factor synthesis
Vit K administration: potentially reverse effect of warfarin
FFP or PCC administration reverses action of warfarin and immediately; can be given with vit K in cases with severe bleeding
———
Antithrombin inhibits thrombin (factor IIa) and VIIa, IXa, Xa, XIa, XIIa
Heparin enhances activity of antithrombin
Principal targets of antithrombin: thrombin and factor Xa

Thrombin-thrombomodulin complex from endothelial cells activates protein C -> activated protein C then requires protein S in order to cleave and inactivate VA, VIIIa

Factor V Leiden mutation produces factor V resistant to inhibition by activated protein C

Question 9

RBC morphology seen in TTP/HUS, DIC and HELLP

Answer 9

Schistocytes
———
RBC morphology

Acanthocytes: spur cells: projections of varying sizes at irregular intervals
Seen in liver disease, abetalipoproteinemia, vitamin E deficiency

Echinocytes: burr cells: smaller and more uniform projections than acanthocytes
Seen in liver disease, ESRD, pyruvate kinase deficiency

Dacrocytes: “teardrop”
Mechanically “squeezed out” of bone marrow
Seen in bone marrow infiltration eg myelofibrosis

Schistocytes: helmet cells: fragmented RBCs
Seen in MAHAs, mechanical hemolysis eg heart valve prosthesis

Degmacytes: bite cells: due to removal of Heinz bodies by splenic macrophages
Seen in G6PD deficiency

Elliptocytes: mutation in genes encoding RBC membrane proteins eg spectrin
Seen in hereditary elliptocytosis

Spherocytes: small spherical cells without central pallor; decreased surface area to volume ratio
Seen in hereditary spherocytosis, AIHA

Macro-ovalocytes: seen in megaloblastic anemia along with hypersegmented PMNs

Target cells: increased surface area to volume ratio
HbC disease, asplenia, liver disease, thalassemia

Sickle cells: occurs with low O2 conditions (high altitude, acidosis)
Also seen in sickle cell anemia

Question 10

Stain needed to visualize Heinz bodies

Answer 10

Supravital stain
———
RBC inclusions

Iron granules: perinuclear mitochondria with excess iron (forming ring in ringed sideroblasts)
Require Prussian blue stain to be visualized
Associated with sideroblastic anemia (eg, lead poisoning, myelodysplastic syndromes, chronic alcohol overuse)

Howell-Jolly bodies: basophilic nuclear remnants (do not contain iron); usually removed by splenic macrophages
Associated with functional hyposplenia (eg sickle cell), asplenia

Basophilic stippling: basophilic ribosomal precipitates (do not contain iron)
Associated with sideroblastic anemias, thalassemias

Pappenheimer bodies: basophilic granules (contains iron)
Associated with sideroblastic anemia

Heinz bodies: denatured and precipitated hemoglobin (contain iron)
Phagocytic removal of Heinz bodies -> bite cells
Requires supravital stain (eg, crystal violet) to be visualized

Question 11

Fanconi anemia is what type of anemia?

Answer 11

Macrocytic
———
Microcytic anemia: MCV < 80
— defective globin chain: thalassemias
— defective heme synthesis: IDA (late), anemia of chronic disease, lead poisoning

Normocytic anemia: MCV 80-100
— nonhemolytic (low reticulocyte index): IDA (early), anemia of chronic disease, aplastic anemia, CKD
— hemolytic (high reticulocyte index)
—— intrinsic: membrane defects (hereditary spherocytosis, PNH), enzyme deficiency (G6PD, pyruvate kinase), hemoglobinopathies (sickle cell, HbC)
—— extrinsic: autoimmune, microangiopathic, macroangiopathic, infections

Macrocytic anemia: MCV > 100
— megaloblastic: defective DNA synthesis (folate deficiency, vitamin B12 deficiency, orotic aciduria), defective DNA repair (Fanconi anemia)
— nonmegaloblastic: Diamond-Blackfan disease, chronic alcohol overuse, liver disease
———
Reticulocyte production index: Also called corrected reticulocyte count
Used to correct falsely elevated reticulocyte count in anemia
Measures appropriate bone marrow response to anemic conditions (effective erythropoiesis)
High RPI (>3) indicates compensatory RBC production; low RPI (<2) indicates inadequate response to correct anemia

RPI = (reticulocyte % × actual Hct)/normal Hct (≈ 45%)

Question 12

Patients with beta thalassemia major can undergo aplastic crisis after infection with:

Answer 12

Parvovirus B-19
———
Microcytic hypochromic anemia

Iron deficiency: decreased iron due to chronic bleeding (eg GI loss, menorrhagia), malnutrition, absorption disorders, GI surgery (eg gastrectomy) or increased demand (eg pregnancy) —> decrease in final step of heme synthesis
Symptoms: fatigue, conjunctival pallor, pica (persistent craving and compulsive eating of nonfood substances), spoon nails (koilonychia)
May manifest as glossitis, cheilosis, Plummer-Vinson syndrome (triad of iron deficiency anemia, esophageal webs, and dysphagia)
Labs: decreased iron, increased TIBC, increased free erythrocyte protoporphyrin, increased RDW, decreased RI
Microcytosis and hypochromasia (increased central pallor)
——
Alpha thalassemia: α-globin gene deletions on chromosome 16 -> increased α-globin synthesis
May have cis deletion (deletions occur on same chromosome) or trans deletion (deletions occur on separate chromosomes)
Normal is αα/αα
Often increased RBC count, in contrast to iron deficiency anemia

1) Alpha thalassemia minima: one alpha globin gene deleted
Silent carrier
2) Alpha thalassemia minor: two alpha globin genes deleted in either cis or trans configuration
Mild microcytic, hypochromic anemia
Cis deletion may worsen outcome for carrier’s offspring
3) Hemoglobin H disease (HbH)/excess beta globin forms (B4): three alpha globin genes deleted
Moderate to severe microcytic, hypochromic anemia
4) Hemoglobin Barts disease: no alpha globins; excess gamma globin forms gamma4
Hydrops fetalis; incompatible with life
——
Beta thalassemia: point mutations in splice sites and promoter sequences on chromosome 11 -> decreased β-globin synthesis
Increasedprevalence in people of Mediterranean descent

1) β-thalassemia minor (heterozygote): β chain is underproduced
Usually asymptomatic
Diagnosis confirmed by increased HbA2 (> 3.5%) on electrophoresis
2) β-thalassemia major (homozygote): β chain is absent -> severe microcytic, hypochromic anemia with target cells and increased anisopoikilocytosis requiring blood transfusion (2° hemochromatosis)
Marrow expansion (“crew cut” on skull x-ray) -> skeletal deformities (eg, “chipmunk” facies). Extramedullary hematopoiesis -> hepatosplenomegaly
Increased risk of parvovirus B19–induced aplastic crisis
HbF (α2γ2), HbA2 (α2δ2)
HbF is protective in the infant and disease becomes symptomatic only after 6 months, when fetal hemoglobin declines
3) HbS/β-thalassemia heterozygote: mild to moderate sickle cell disease depending on amount of β-globin production

Question 13

A 5 year old child complains of fatigue that is only mildly relieved with rest. Upon examination he was noted to have microcytic hypochromic anemia with noted basophilic stippling on microscopy. You diagnose him with lead poisoning. What is the most probable cause?

Answer 13

Chipped paint in old houses
———
Microcytic hypochromic anemia

Lead poisoning: Lead inhibits ferrochelatase and ALA dehydratase -> decreased heme synthesis and increases RBC protoporphyrin
Also inhibits rRNA degradation -> RBCs retain aggregates of rRNA (basophilic stippling)

Symptoms of LEAD poisoning: Lead Lines on gingivae (Burton lines) and on metaphyses of long bones on x-ray, Encephalopathy and Erythrocyte basophilic stippling, Abdominal colic and sideroblastic Anemia, Drops—wrist and foot drop
Tx: chelation with succimer, EDTA, dimercaprol
Exposure risk increased in old houses with chipped paint (children) and workplace (adults)
——
Sideroblastic anemia: causes: genetic (eg, X-linked defect in ALA synthase gene), acquired (myelodysplastic syndromes), and reversible (alcohol is most common; also lead poisoning, vitamin B6 deficiency, copper deficiency, drugs [eg, isoniazid, linezolid])
Lab findings: increased iron, normal/decreased TIBC, increased ferritin
Ringed sideroblasts (with iron-laden, Prussian blue-stained mitochondria) seen in bone marrow
PBS: basophilic stippling of RBCs
Some acquired variants may be normocytic or macrocytic
Tx: pyridoxine (B6, cofactor for ALA synthase)
——
Transferrin: transports iron in blood
TIBC: indirectly measures transferrin
Ferritin: primary iron storage in body; evolutionary reasoning—pathogens use circulating iron to thrive -> body adapted a system in which iron is stored within the cells of the body and prevents pathogens from acquiring circulating iron
Tsat = serum iron/TIBC
———
Iron studies

IDA: decreased serum iron, increased TIBC, decreased ferritin, decreased Tsat

Chronic disease: decreased serum iron, increased TIBC, increased ferritin, normal or decreased Tsat

Hemochromatosis: increased serum iron, decreased TIBC, increased ferritin, increased Tsat

Pregnancy/OCP use: normal serum iron and ferritin, increased TIBC, decreased Tsat

Question 14

An anemic patient presents with macrocytic anemia with hypersegmented neutrophils. Upon further workup she had elevated homocysteine and MMA. What is the most probable cause of her anemia?

Answer 14

Cobalamin deficiency
———
Macrocytic anemias

Megaloblastic anemia: impaired DNA synthesis -> maturation of nucleus of precursor cells in bone marrow delayed relative to maturation of cytoplasm
Causes: vitamin B12 deficiency, folate deficiency, medications (eg, hydroxyurea, phenytoin, methotrexate, sulfa drugs)
Findings: RBC macrocytosis, hypersegmented neutrophils, glossitis

Folate deficiency: causes: malnutrition (eg, chronic alcohol overuse), malabsorption, drugs (eg, methotrexate, trimethoprim, phenytoin), increased requirement (eg, hemolytic anemia, pregnancy)
Increased homocysteine, normal MMA, no neuro symptoms unlike B12 deficiency

Vitamin B12 (cobalamin) deficiency: causes: pernicious anemia, malabsorption (eg, Crohn disease), pancreatic insufficiency, gastrectomy, insufficient intake (eg, veganism), Diphyllobothrium latum (fish tapeworm)
Increased homocysteine and MMA
Neurologic symptoms: reversible dementia, subacute combined degeneration (due to involvement of B12 in fatty acid pathways and myelin synthesis): spinocerebellar tract, lateral corticospinal tract, dorsal column dysfunction
Folate supplementation in vitamin B12 deficiency can correct anemia, but worsens neurologic symptoms
Historically diagnosed with the Schilling test, a test that determines if the cause is dietary insufficiency vs malabsorption
Anemia 2° to insufficient intake may take several years to develop due to liver’s ability to store B12 (vs folate deficiency, which takes weeks to months)

Orotic aciduria: autosomal recessive inability to convert orotic acid to UMP (de novo pyrimidine synthesis pathway) because of defect in UMP synthase
In children: failure to thrive, developmental delay, and megaloblastic anemia refractory to folate and B12
No hyperammonemia (vs ornithine transcarbamylase deficiency— orotic acid with hyperammonemia)
Tx: uridine monophosphate or uridine triacetate to bypass mutated enzyme
———
Macrocytic, nonmegaloblastic anemia: caused by chronic alcohol overuse, liver disease
Normal DNA synthesis; RBC macrocytosis without hypersegmented neutrophils

Diamond-Blackfan anemia: congenital form of pure red cell aplasia (vsFanconi anemia, which causes pancytopenia)
Rapid-onset anemia within 1st year of life due to intrinsic defect in erythroid progenitor cells
Increase in percentage of HbF but decreased total Hgb
Presentation: short stature, craniofacial abnormalities and upper extremity malformations (triphalangeal thumbs) in up to 50% of cases

Question 15

Findings on blood smear in intravascular hemolysis

Answer 15

Decreased haptoglobin, increased schistocytes
———
Normocytic, normochromic anemia: classified as nonhemolytic or hemolytic
Hemolytic anemias: further classified according to the cause of the hemolysis (intrinsic vs extrinsic to the RBC) and by the location of the hemolysis (intravascular vs extravascular)
Hemolysis can lead to increases in LDH, reticulocytes, unconjugated bilirubin, pigmented gallstones, and urobilinogen in urine
———
Intravascular hemolysis: findings: decreased haptoglobin, increased schistocytes on blood smear
Characteristic hemoglobinuria, hemosiderinuria, and urobilinogen in urine
Notable causes: mechanical hemolysis (eg, prosthetic valve), PNH, MAHA

Extravascular hemolysis: Mechanism: macrophages in spleen clear RBCs
Findings: spherocytes in peripheral smear (most commonly due to hereditary spherocytosis and AIHA), no hemoglobinuria/hemosiderinuria
Can present with urobilinogen in urine
———
Anemia of chronic disease: normocytic but can become microcytic
Inflammation (eg, increased IL-6) -> increased hepcidin (released by liver, binds ferroportin on intestinal mucosal cells and macrophages, thus inhibiting iron transport) -> decreased release of iron from macrophages and decreased iron absorption from gut
Associated with conditions such as chronic infections, neoplastic disorders, CKD and autoimmune diseases (eg, SLE, RA)
Tx: address underlying cause of inflammation, judicious use of blood transfusion, consider erythropoiesis-stimulating agents such as EPO (eg, in CKD)
———
Aplastic anemia: failure or destruction of hematopoietic stem cells
Causes: radiation, viral agents (eg EBV, HIV, hepatitis viruses), Fanconi anemia (autosomal recessive DNA repair defect -> bone marrow failure; normocytosis or macrocytosis), idiopathic (immune mediated, primary stem cell defect; may follow acute hepatitis), drugs (eg benzene, chloramphenicol, aklylating agents, antimetabolites)

Labs: decreased reticulocyte count, increased EPO
Pancytopenia characterized by anemia, leukopenia, and thrombocytopenia (not to be confused with aplastic crisis, which causes anemia only)
Normal cell morphology, but hypocellular bone marrow with fatty infiltration (dry bone marrow tap)
Symptoms: fatigue, malaise, pallor, purpura, mucosal bleeding, petechiae, infection

Tx: withdrawal of offending agent, immunosuppressive regimens (eg, antithymocyte globulin, cyclosporine), bone marrow allograft, RBC/platelet transfusion, bone marrow stimulation (eg, GM-CSF)

Question 16

A patient experiences back pain and hemoglobinuria a few days after being started on an unrecalled diuretic. PBS shows bite cells. Your diagnosis is:

Answer 16

G6PD deficiency
———
Intrinsic hemolytic anemias

Hereditary spherocytosis: autosomal dominant
Defect in proteins interacting with RBC membrane skeleton and plasma membrane (eg, ankyrin, band 3, protein 4.2, spectrin)
Small, round RBCs with less surface area and no central pallor (inc MCHC) -> premature removal by spleen (extravascular hemolysis)
Findings: splenomegaly, pigmented gallstones, aplastic crisis (parvovirus B19)
Labs: decreased mean fluorescence of RBCs in eosin-5-maleimide (EMA) binding test, increased fragility in osmotic fragility test; normal to decreased MCV with abundance of RBCs
Tx: splenectomy
—
G6PD deficiency: X-linked recessive G6PD defect -> decreased NADPH -> decreased reduced glutathione -> increased RBC susceptibility to oxidative stress (eg sulfa drugs, antimalarials, fava beans) -> intra- and extravascular hemolysis
Sx: back pain and hemoglobinuria few days after oxidant stress
Labs: PBS: RBCs with Heinz bodies and bite cells
—
Pyruvate kinase deficiency: autosomal recessive PK defect -> decreased ATP -> rigid RBCs -> extravascular hemolysis
Increased 2,3BPG -> increased Hgb affinity for O2
Hemolytic anemia in newborn
PBS: burr cells
—

Question 17

What causes hematuria in sickle cell disease?

Answer 17

Sickling in renal medulla -> renal papillary necrosis
———
Other intrinsic hemolytic anemias:

PNH: hematopoietic stem cell mutation -> complement-mediated intravascular hemolysis, especially at night
Acquired PIGA mutation -> impaired GPI anchor synthesis for decay-accelerating factor (DAF/CD55) and membrane inhibitor of reactive lysis (MIRL/ CD59), which protect RBC membrane from complement
Triad: Coombs ⊝ hemolytic anemia, pancytopenia, venous thrombosis (eg, BuddChiari syndrome)
Pink/red urine in morning
Associated with aplastic anemia, acute leukemias
Labs: CD55/59 ⊝ RBCs on flow cytometry
Tx: eculizumab (targets terminal complement protein C5)
—
Sickle cell anemia: point mutation in β-globin gene -> single amino acid substitution (glutamic acid to valine)
Mutant HbA is termed HbS
Causes extravascular and intravascular hemolysis
Pathogenesis: low O2, high altitude, or acidosis precipitates sickling (deoxygenated HbS polymerizes) -> anemia, vaso-occlusive disease
Newborns initially asymptomatic because of increased HbF and decreased HbS
Heterozygotes (sickle cell trait) have resistance to malaria
Most common autosomal recessive disease in Black population
Sickle cells are crescent-shaped RBCs
“Crew cut” on skull x-ray due to marrow expansion from erythropoiesis (also seen in thalassemias)

Complications in sickle cell disease:
Aplastic crisis (transient arrest of erythropoiesis due to parvovirus B19)
Autosplenectomy (Howell-Jolly bodies) -> increased risk of infection by encapsulated organisms (eg, S pneumoniae)
Splenic infarct/sequestration crisis
Salmonella osteomyelitis
Painful vaso-occlusive crises: dactylitis (painful swelling of hands/feet), priapism, acute chest syndrome (respiratory distress, new pulmonary infiltrates on CXR, common cause of death), avascular necrosis, stroke
Sickling in renal medulla (dec Po2 ) -> renal papillary necrosis -> hematuria
Hb electrophoresis: dec HbA, inc HbF, inc HbS
Treatment: hydroxyurea (reduces HbF), hydration
—
HbC disease: glutamic acid–to-lycine (lysine) mutation in β-globin
Causes extravascular hemolysis
Patients with HbSC (1 of each mutant gene) have milder disease than HbSS patients
Blood smear in homozygotes: hemoglobin crystals inside RBCs, target cells

Question 18

Patients with cold AIHA can get painful, blue fingers upon exposure to cold. What is the pathophysiology of this mechanism?

Answer 18

IgM + complement cause RBC agglutination and extravascular hemolysis
———
Extrinsic hemolytic anemias

AIHA: normocytic anemia, usually idiopathic and Coombs ⊕
Two types: Warm AIHA: chronic anemia in which primarily IgG causes extravascular hemolysis
Seen in SLE and CLL and with certain drugs (eg, β-lactams, α-methyldopa)
Cold AIHA: acute anemia in which primarily IgM + complement cause RBC agglutination and extravascular hemolysis upon exposure to cold -> painful, blue fingers and toes
Seen in CLL, Mycoplasma pneumoniae infections, infectious mononucleosis
Spherocytes and agglutinated RBCs on PBS
Warm AIHA treatment: steroids, rituximab, splenectomy (if refractory)
Cold AIHA treatment: cold avoidance, rituximab
——
Microangiopathic hemolytic anemia: RBCs damaged when passing through obstructed or narrowed vessels
Causes intravascular hemolysis
Seen in DIC, TTP/HUS, SLE, HELLP syndrome, HTN emergency
PBS: schistocytes due to mechanical destruction of RBCs
——
Macroangiopathic hemolytic anemia: prosthetic heart valves and aortic stenosis: hemolytic anemia 2° to mechanical destruction of RBCs
PBS: schistocytes
——
Hemolytic anemia due to infection: increased RBC destruction (eg malaria, Babesia)
———
Leukopenias:

Neutropenia: Absolute neutrophil count < 1500 cells/mm3
Severe infections typical when < 500 cells/mm3
Causes: sepsis/postinfection, drugs (including chemotherapy), aplastic anemia, SLE, radiation

Lymphopenia: Absolute lymphocyte count < 1500 cells/mm3 (<3000 cells/mm³ in children)
Causes: HIV, DiGeorge syndrome, SCID, SLE, corticosteroids, radiation, sepsis, postoperative

Eosinopenia: Absolute eosinophil count < 30 cells/mm3
Causes: Cushing syndrome, corticosteroids

Corticosteroids cause neutrophilia, despite causing eosinopenia and lymphopenia
Corticosteroids decrease activation of neutrophil adhesion molecules, impairing migration out of the vasculature to sites of inflammation
In contrast, corticosteroids sequester eosinophils in lymph nodes and cause apoptosis of lymphocytes

Question 19

Cause of tea-colored urine in porphyria cutanea tarda

Answer 19

Accumulation of uroporphyrin
——
Porphyrias: hereditary or acquired conditions of defective heme synthesis that lead to the accumulation of heme precursors
Lead: inhibits specific enzymes needed in heme synthesis
——
Lead poisoning: affects ferrochelatase and ALA dehydratase
Accumulates protoporphyrin and ALA in blood
Microcytic anemia (basophilic stippling in peripheral smear, ringed sideroblasts in bone marrow), GI and kidney disease
Children: exposure to lead paint -> mental deterioration
Adults: environmental exposure (eg, batteries, ammunition) -> headache, memory loss, demyelination (peripheral neuropathy)
——
Acute intermittent porphyria: porphobilinogen deaminase deficiency (autosomal dominant mutation)
Accumulation of porphobilinogen and ALA
Sx: painful abdomen, port wine–colored pee, polyneuropathy, psychological disturbances
Precipitated by factors that increase ALA synthase (eg, drugs [CYP450 inducers], alcohol, starvation)
Tx: hemin and glucose inhibit ALA synthase
——
Porphyria cutanea tarda: most common porphyria
Affects uroporphyrinogen decarboxylase
Accumulates uroporphyrin (tea-colored urine)
Blistering cutaneous photosensitivity and hyperpigmentation
Exacerbated with alcohol consumption
Causes: familial, hepatitis C
Tx: phlebotomy, sun avoidance, antimalarials (eg, HCQ)

Question 20

Diagnostic that tests function of factors I, II, V, VII and X

Answer 20

Protime
———
Acute iron poisoning: high mortality rate associated with accidental ingestion by children (adult iron tablets may look like candy)
Mechanism: cell death due to formation of free radicals and peroxidation of membrane lipids
Sx: abdominal pain, vomiting, GI bleeding
Radiopaque pill seen on x-ray
May progress to anion gap metabolic acidosis and multiorgan failure
Leads to scarring with GI obstruction
Tx: chelation (eg, deferoxamine, deferasirox), gastric lavage
——
Chronic iron poisoning: seen in patients with 1° (hereditary) or 2° (eg, chronic blood transfusions for thalassemia or sickle cell disease) hemochromatosis
Sx: arthropathy, cirrhosis, cardiomyopathy, diabetes mellitus and skin pigmentation (“bronze diabetes”), hypogonadism
Tx: phlebotomy for patients without anemia; chelation
———
Coagulation disorders:

PT: tests function of common and extrinsic pathway (factors I, II, V, VII, and X)
Defect -> increased PT

INR: patient PT/control PT; normal = 1, prolonged > 1
Most common test used to follow patients on warfarin, which prolongs INR

PTT: tests function of common and intrinsic pathway (all factors except VII and XIII)
Defect -> increased PTT

Coagulation disorders: clotting factor deficiencies or acquired factor inhibitors (most commonly against factor VIII)
Diagnosed with a mixing study, in which normal plasma is added to patient’s plasma
Clotting factor deficiencies should correct the PT/PTT, whereas factor inhibitors will not correct
—
Hemophilia A, B or C: normal PT, increased PTT
Intrinsic pathway coagulation defect (increased PTT)
A: deficiency of factor VIII; X-linked recessive
B: deficiency of factor IX; X-linked recessive
C: deficiency of factor XI; autosomal recessive
Hemorrhage in hemophilia: hemarthroses (bleeding into joints, eg, knee), easy bruising, bleeding after trauma or surgery (eg, dental procedures)
Tx: desmopressin, factor VIII concentrate, emicizumab (A); factor IX concentrate (B); factor XI concentrate (C)
—
Vitamin K deficiency: increased PT and PTT
General coagulation defect
Bleeding time normal
Decreased activity of factors II, VII, IX, X, protein C, protein S

Question 21

Autosomal recessive disease where blood smear shows absence of platelet clumping

Answer 21

Glanzmann thrombasthenia
———
Platelet disorders: increased bleeding time, mucous membrane bleeding, and microhemorrhages (eg, petechiae, epistaxis)
Platelet count usually low, but may be normal in qualitative disorders
—
Bernard-Soulier syndrome: normal/decreased platelet count, increased bleeding time
Autosomal recessive defect in adhesion
Decreased GpIb -> increased platelet-to-vWF adhesion
Labs: abnormal ristocetin test, large platelets
—
Glanzmann thrombasthenia: normal platelet count, increased bleeding time
Autosomal recessive defect in aggregation
Decreased GpIIb/IIIa (decreased integrin αIIb β3 ) -> decreased platelet-to-platelet aggregation and defective platelet plug formation
Labs: blood smear shows no platelet clumping
—
Immune thrombocytopenia: decreased platelet count, increased bleeding time
Destruction of platelets in spleen
Anti-GpIIb/IIIa antibodies -> splenic macrophages phagocytose platelets
May be idiopathic or 2° to autoimmune disorders (eg, SLE), viral illness (eg, HIV, HCV), malignancy (eg, CLL), or drug reactions
Labs: increased megakaryocytes on bone marrow biopsy, decreased platelet count
Tx: steroids, IVIG, rituximab, TPO receptor agonists (eg, eltrombopag, romiplostim), or splenectomy for refractory ITP
———
Thrombotic microangiopathies

TTP: typically affects females
Inhibition or deficiency of ADAMTS13 (vWF metalloprotease) -> decreased degradation of vWF multimers -> increased large vWF multimers -> increased platelet adhesion and aggregation (microthrombi formation)
Findings: triad (thrombocytopenia, MAHA, AKI) + neurologic symptoms
Tx: plasma exchange, steroids, rituximab

HUS: typically affects children
Commonly caused by Shiga toxin-producing Escherichia coli (STEC) infection (serotype O157:H7)
Findings: triad + bloody diarrhea
Tx: supportive care

Normal PT and PTT helps distinguish TTP and HUS (coagulation pathway is not activated) from DIC (coagulation pathway is activated)

Question 22

A patient was started on warfarin due to a cardiac condition. After a two days he started to develop skin necrosis. He was determined to have decreased ability to inactivate factors Va and VIIIa. What hereditary disease could the patient have?

Answer 22

Protein C or S deficiency
———
Mixed platelet and coagulation disorders

von Willebrand disease: normal PC and PT, normal or elevated BT, elevated PTT
Intrinsic pathway coagulation defect: decreased vWF -> increased PTT (vWF carries/protects factor VIII)
Defect in platelet plug formation: decreased vWF ->defect in platelet-to-vWF adhesion
Most are autosomal dominant
Mild but most common inherited bleeding disorder
No platelet aggregation with ristocetin cofactor assay
Tx: desmopressin, which releases vWF stored in endothelium

DIC: decreased platelet count, increased bleeding time, PT and PTT
Widespread clotting factor activation -> deficiency in clotting factors -> bleeding state
Causes: snake bite, sepsis (gram neg), trauma, obstetric complications, acute pancreatitis, malignancy, nephrotic syndrome, transfusion
Labs: schistocytes, increased fibrin degradation products (D-dimers), decreased fibrinogen, decreased factors V and VIII
———
Hereditary thrombophilias: autosomal dominant; hypercoagulable state

Antithrombin deficiency: no direct effect on PT/PTT or thrombin time but diminishes increase in PTT following standard heparin dosing
Can be acquired: renal failure/nephrotic syndrome -> antithrombin loss in urine -> decreased inhibition of factors IIa and Xa
—
Factor V Leiden: production of mutant factor V (guanine -> adenine DNA point mutation -> Arg506In mutation near cleavage site) that is resistant to degradation by activated protein C
Complications: DVT, cerebral vein thrombosis, recurrent pregnancy loss
—
Protein C or Protein S deficiency: decreased ability to inactivate factors Va and VIIIa
Increased risk of warfarin-induced skin necrosis
—
Prothrombin G20210A mutation: Point mutation in 3′ untranslated region -> increased production of prothrombin -> increased plasma levels and venous clots

Question 23

Blood product that contains factors II, VII, IX and X and proteins C and S

Answer 23

Prothrombin complex concentrate
———
Blood transfusion therapy

pRBCs: acute blood loss, severe anemia

Platelets: increases PC by 5000/mm3/unit
Stops significant bleeding (thrombocytopenia, qualitative platelet defects)

FFP/prothrombin complex concentrate: increases coagulation factor levels
Contains all coagulation factors and plasma proteins
PCC: contains factors II, VII, IX and X and proteins C and S
Used for cirrhosis and immediate antiocoagulation reversal

Cryoprecipitate: contains fibrinogen, factor VIII, factor XIII, vWF and fibronectin
Used for coagulation factor deficiencies involving fibrinogen and factor VIII

Blood transfusion risks: infection transmission, transfusion reactions, iron overload (secondary hemochromatosis), hypocalcemia (citrate is a Ca2+ chelator and hyperkalemia (RBCs may lyse in old blood units)
———
Leukemia: lymphoid or myeloid neoplasm with widespread involvement of bone marrow
Tumor cells found on PBS

Lymphoma: discrete tumor mass arising from lymph nodes
———
Hodgkins vs NHL: both may present with constitutional (“B”) signs/sx: low grade fever, night sweats, weight loss

Hodgkins: localized, single group of nodes with contiguous spread (stage is strongest predictor of prognosis); Better prognosis
Reed-Sternberg cells: distinctive tumor giant cells; binucleate or bilobed with the 2 halves as mirror images (“owl eyes”); CD15+ and CD30+ B-cell origin
Bimodal distribution: young adulthood and > 55 years; more common in males except for nodular sclerosing type
Associated with EBV

Subtypes:
Nodular sclerosis: most common subtype
Lymphocyte-rich: best prognosis
Mixed cellularity: eosinophilia; seen in immunocompromised patients
Lymphocyte-depleted: worst prognosis; seen in immunocompromised patients
—
NHL: multiple lymph nodes involved; extranodal involvement common; noncontiguous spread
Worse prognosis
Majority involve B cells; a few are of T-cell lineage
Can affect children and adults
May be associated with autoimmune diseases and viral infections (eg, HIV, EBV, HTLV)

Question 24

Genetic aberration in follicular lymphoma

Answer 24

t (14;18)
———
NHL

Neoplasms of mature B cells:

Burkitt lymphoma: occurs in adolescents or young adults
t (8;14) translocation of c-myc (8) and heavy chain Ig (14)
“Starry sky” appearance, sheets of lymphocytes with interspersed “tingible body” macrophages
Associated with EBV
Jaw lesion in endemic form in Africa; pelvis or abdomen in sporadic form

DLBCL: usually occurs in older adults but 20% in children
Mutations in BCL-2, BCL-6
Most common type of NHL in adults

Follicular lymphoma: occurs in adults
t (14;18): translocation of heavy-chain Ig (14) and BCL-2 (18)
Indolent course with painless waxing and waning lymphadenopathy

Mantle cell lymphoma: adult males&raquo_space; adult females
t(11;14): translocation of cyclin D1 (11) and heavy chain Ig (14), CD5+
Very aggressive, typically presents in late stage

Marginal zone lymphoma: adults
t (11;18)
Associated with chronic inflammation (eg, Sjögren syndrome, chronic gastritis [MALT lymphoma; may regress with H pylori eradication])

Primary CNS lymphoma: occurs in adults
Related to EBV
Associated with HIV/AIDS
Considered an AIDS-defining illness
Variable presentation: confusion, memory loss, seizures
CNS mass (often single, ring-enhancing lesion) on MRI in immunocompromised patients
Needs to be distinguished from toxoplasmosis via CSF analysis or other lab tests
—
Neoplasms of mature T cells

Adult T cell lymphoma: caused by HTLV (associated with IV drug use)
Common in Japan, West Africa and Carribean
Presents with cutaneous lesions, lytic bone lesions and hypercalcemia

Mycosis fungoides/Sezary syndrome: occurs in adults

Mycosis fungoides: cutaneous T-cell lymphoma presenting as skin patches and plaques, characterized by atypical CD4+ cells with “cerebriform” nuclei and intraepidermal neoplastic cell aggregates (Pautrier microabscess)
May progress to Sezary syndrome (T-cell leukemia)

Question 25

Patient presents with back pain and fatigue. On lab workup there was noted increased creatinine and serum calcium. Xray shows punched-out lesions of the bones. What is the expected result of the bone marrow analysis?

Answer 25

> 10% monoclonal plasma cells with clock face chromatin and intracytoplasmic inclusions containing IgG
———
Plasma cell dyscrasias: characterized by monoclonal immunoglobulin (paraprotein) overproduction due to plasma cell disorder
Labs: serum protein electrophoresis (SPEP) or free light chain (FLC) assay for initial tests; M spike on SPEP represents overproduction of a monoclonal Ig fragment
For urinalysis, use 24-hr urine protein electrophoresis (UPEP) to detect light chain, as routine urine dipstick detects only albumin
Confirm with bone marrow biopsy

Multiple myeloma: overproduction of IgG (55% of cases) > IgA
Clinical features: hypercalcemia, renal involvement, anemia, bone lytic lesions (“punched out” on Xray, causing back pain)
PBS: RBCs in rouleaux formation (stacked like poker chips)
Urinalysis: Ig light chains (Bence Jones proteinuria) with negative urine dipstick
Bone marrow analysis: >10% monoclonal plasma cells with clock-face chromatin and intracytoplasmic inclusions containing IgG
Complications: increased infection risk, primary amyloidosis
—
Waldenstrom macroglobulinemia: overproduction of IgM (IgM is largest Ig hence macro)
Clinical features: peripheral neuropathy, no CRAB findings (eg MM), hyperviscosity syndrome (headache, blurry vision, Raynaud phenomenon, retinal hemorrhages)
Bone marrow analysis: >10% small lymphocytes with intranuclear pseudoinclusions containing IgM (lymphoplasmacytic lymphoma)
Complication: thrombosis
—
Monoclonal gammopathy of undetermined significance: overproduction of any Ig type
Usually asymptomatic
Bone marrow analysis: <10% monoclonal plasma cells
Complications: 1-2% risk per year of transitioning to multiple myeloma
—
MDS: stem cell disorders involving ineffective hematopoiesis -> defects in cell maturation of nonlymphoid lineages
Bone marrow blasts <20% (vs >20% in AML)
Caused by de novo mutations or environmental exposure (eg, radiation, benzene, chemotherapy)
Risk of transformation to AML

Pseudo-Pelger-Huet anomaly: neutrophils with bilobed (“duet”) nuclei
Associated with MDS or drugs eg immunosuppressants

Question 26

Smudge cells on PBS were noted. Which types of B cells are probably malignant?

Answer 26

CD20, CD23, CD5
———
Leukemias: unregulated growth and differentiation of WBCs in bone marrow -> marrow failure -> anemia (dec RBCs), infections (dec mature WBCs), and hemorrhage (dec platelets)
Usually presents with increased circulating WBCs (malignant leukocytes in blood), although some cases present with normal/decreased WBCs
Leukemic cell infiltration of liver, spleen, lymph nodes, and skin (leukemia cutis) possible
—
Types

Lymphoid neoplasms

ALL: most frequently occurs in children; less common in adults (worse prognosis)
T-cell ALL can present as mediastinal mass (presenting as SVC-like syndrome)
Associated with Down syndrome
Peripheral blood and bone marrow have increased lymphoblasts
TdT+ (marker of pre-T and pre-B cells), CD10+ (marker of pre-B cells)
Most responsive to therapy
May spread to CNS and testes
t(12;21): better prognosis
t(9;22) (Philadelphia chromosome): worse prognosis

CLL/small lymphocytic lymphoma: Age > 60 years
Most common adult leukemia
CD20+, CD23+, CD5+ B-cell neoplasm
Often asymptomatic, progresses slowly
Smudge cells in peripheral blood smear; autoimmune hemolytic anemia
Richter transformation: CLL/SLL transformation into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL)

Hairy cell leukemia: mature B-cell tumor that commonly affects adult males
Cells have filamentous, hair-like projections (fuzzy appearing on LM)
Peripheral lymphadenopathy is uncommon
Causes marrow fibrosis -> drytap on aspiration
Patients usually present with massive splenomegaly and pancytopenia
Dx: Stains TRAP (Tartrate-Resistant Acid Phosphatase)⊕
TRAP stain largely replaced with flow cytometry
Associated with BRAF mutations
Tx: purine analogs (cladribine, pentostatin)
——
Myeloid neoplasms:

AML: Median onset 65 years
Dx: Auer rods; myeloperoxidase ⊕ cytoplasmic inclusions seen mostly in APL (formerly M3 AML); circulating myeloblasts on peripheral smear
Risk factors: prior exposure to alkylating chemotherapy, radiation, myeloproliferative disorders, Down syndrome (typically acute megakaryoblastic leukemia [formerly M7 AML])

APL: t(15;17), responds to all-trans retinoic acid (vitamin A) and arsenic trioxide, which induce differentiation of promyelocytes
Commonly presents as DIC
—
CML: peak incidence: 45—85 years; median age: 64 years
Defined by the Philadelphia chromosome (t[9;22], BCR-ABL) and myeloid stem cell proliferation
Presents with dysregulated production of mature and maturing granulocytes (eg, neutrophils, metamyelocytes, myelocytes, basophils) and splenomegaly
May accelerate and transform to AML or ALL (“blast crisis”)
Labs: decreased RBCs, increased WBCs and platelets, (-) JAK2 mutations
Responds to BCR-ABL tyrosine kinase inhibitors (eg, imatinib)

Question 27

Atypical megakaryocte hyperplasia in myelofibrosis causes an increase in the secretion of this enzyme which in turn increases fibroblast activity

Answer 27

TGF-B
———
Myeloproliferative neoplasms: malignant hematopoietic neoplasms with varying impacts on WBCs and cell lines

Polycythemia vera: Increased RBCs, usually due to acquired JAK2 mutation
May present as intense itching after shower (aquagenic pruritus)
Rare but classic symptom is erythromelalgia (severe, burning pain and red-blue coloration) due to episodic blood clots in vessels of the extremities
Decreased EPO due to negative feedback (vs 2° polycythemia, which presents with endogenous or artificially increased EPO)
Labs: increased WBCs, RBCs, platelets; (+) JAK2 mutation
Tx: phlebotomy, hydroxyurea, ruxolitinib (JAK1/2 inhibitor)

Essential thrombocythemia: massive proliferation of megakaryocytes and platelets
Sx: bleeding and thrombosis; erythromelalgia may occur
Blood smear: markedly increased number of platelets, which may be large or otherwise abnormally formed
Other labs: (+) JAK2 mutation

Myelofibrosis: Atypical megakaryocyte hyperplasia bone -> increased TGF-β secretion -> increasedfibroblast activity ->obliteration of bone marrow with fibrosis
Associated with massive splenomegaly and “teardrop” RBCs
Decreased RBCs, variable counts of WBCs and increased platelets, (+) JAK2 mutation
———
Relative polycythemia: seen in decreased plasma volume eg dehydration, burns

Appropriate absolute polycythemia: increase in RBC mass due to decreased O2 saturation; increased EPO
Seen in lung disease, CHD, high altitudes

Inappropriate absolute polycythemia: increased EPO levels increase RBC mass eg exogenous EPO, EPO-secreting HCC or RCC
———
Leukemoid reaction: reactive neutrophilia >50,000 cells/mm3
Neutrophil morphology: toxic granulation, Dohle bodies, cytoplasmic vacuoles
Increased LAP score
Normal eosinophils and basophils

Compare to CML: myeloproliferative neoplasm (+) for BCR-ABL
Neutrophils: Pseudo-Pelger-Huet anomaly
Decreased LAP score due to decreased LAP in malignant neutrophils
Increased eosinophils and basophils

Question 28

Characteristic electron microscopy findings in Langerhans cell histiocytosis

Answer 28

Birbeck granules
———
Chromosomal translocations

t(8;14): Burkitt (Burk-8) lymphoma (c-myc activation)
t(11;14): Mantle cell lymphoma (cyclin D1 activation)
t(11;18): Marginal zone lymphoma
t(14;18): Follicular lymphoma (BCL-2 activation)
t(15;17): APL (formerly M3 type of AML)
t(9;22) (Philadelphia chromosome) CML (BCR-ABL hybrid), ALL (less common)

Ig heavy chain genes on chromosome14 are constitutively expressed -> when other genes (eg, c-myc and BCL-2) are translocated next to this heavy chain gene region, they are overexpressed
———
Langerhans cell histiocytosis: collective group of proliferative disorders of Langerhans cells
Presents in a child as lytic bone lesions and skin rash or as recurrent otitis media with a mass involving the mastoid bone
Cells are functionally immature and do not effectively stimulate primary T cells via antigen presentation
Cells express S-100 (mesodermal origin) and CD1a
Birbeck granules (“tennis rackets” or rodshaped on EM) are characteristic

Question 29

Tumor lysis syndrome can be prevented by:

Answer 29

Aggressive hydration
———
Tumor lysis syndrome: oncologic emergency triggered by massive tumor cell lysis, seen most often with lymphomas/leukemias
Usually caused by treatment initiation, but can occur spontaneously with fast-growing cancers
Release of K+ -> hyperkalemia, release of PO4 3– -> hyperphosphatemia, hypocalcemia due to Ca2+ sequestration by PO4 3–
Increased nucleic acid breakdown ->hyperuricemia -> AKI
Prevention and treatment: aggressive hydration, allopurinol, rasburicase
———
Hemophagocytic lymphohistiocytosis: systemic overactivation of macrophages and cytotoxic T cells fever, pancytopenia, hepatosplenomegaly, increased serum ferritin levels
Can be inherited or 2° to strong immunologic activation (eg, after EBV infection, malignancy)
Bone marrow biopsy: macrophages phagocytosing marrow element

Question 30

Medication given when starting warfarin in order to enable anticoagulation during initial, transient hypercoagulable state caused by warfarin

Answer 30

Heparin (“bridging”)
———
Heparin: activates antithrombin which decreases action of factors IIa (thrombin) and Xa
Acts on blood
Short half life; rapid onset (hours)
Used for immediate anticoagulation for pulmonary embolism (PE), acute coronary syndrome, MI, deep venous thrombosis (DVT)
Used during pregnancy (does not cross placenta)
Monitor PTT when using (intrinsic pathway)

Adverse effects: bleeding (reverse with protamine sulfate), heparin-induced thrombocytopenia (HIT), osteoporosis (with long-term use), drug-drug interactions
—HIT type 1: mild (platelets >100,000/mm3), transient, nonimmunologic drop in platelet count that typically occurs within the first 2 days of heparin administration; not clinically significant
—HIT type 2: development of IgG antibodies against heparin-bound platelet factor 4 (PF4) that typically occurs 5–10 days after heparin administration
Antibody-heparin-PF4 complex binds and activates platelets removal by splenic macrophages and thrombosis -> decreased platelet count
Highest risk with unfractionated heparin

Low-molecular-weight heparins (eg, enoxaparin, dalteparin) act mainly on factor Xa
Fondaparinux acts only on factor Xa
Have better bioavailability and 2–4× longer half life than unfractionated heparin; can be administered subcutaneously and without lab monitoring
LMWHs undergo renal clearance (vs hepatic clearance of unfractionated heparin) and must be used with caution in patients with renal insufficiency
Not easily reversible
——
Warfarin: inhibits vitamin K epoxide reductase by competing with vitamin K -> inhibition of vitamin K-dependent γ-carboxylation of clotting factors II, VII, IX, and X and proteins C and S
Metabolism affected by polymorphisms in the gene for vitamin K epoxide reductase complex (VKORC1)
Laboratory assay: has effect on extrinsic pathway and increased PT
Long half-life; slow onset of action due to limitation by half lives of normal clotting factors (days)

Used for chronic anticoagulation (eg, venous thromboembolism prophylaxis and prevention of stroke in atrial fibrillation)
Not used in pregnant patients (because warfarin, unlike heparin, crosses placenta)
Monitor PT/INR during usage (extrinsic pathway)

Adverse effects: bleeding, teratogenic effects, skin/tissue necrosis, drug-drug interactions (metabolized by cytochrome P-450 [CYP2C9])
Initial risk of hypercoagulation: protein C has shorter half-life than factors II and X
Existing protein C depletes before existing factors II and X deplete, and before warfarin can reduce factors II and X production -> hypercoagulation
Skin/tissue necrosis within first few days of large doses believed to be due to small vessel microthrombosis

Heparin “bridging”: heparin frequently used when starting warfarin
Heparin’s activation of antithrombin enables anticoagulation during initial, transient hypercoagulable state caused by warfarin
Initial heparin therapy reduces risk of recurrent venous thromboembolism and skin/ tissue necrosis

For reversal of warfarin, give vitamin K
For rapid reversal, give FFP or PCC

Question 31

Reversal agent for bivalirudin

Answer 31

Andexanet alfa
———
Direct coagulation factor inhibitors

Bivalirudin, argatroban, dabigatran: directly inhibits thrombin (factor IIa)
Dabigatran is the only oral agent in this class
Used for VTE, AF, HIT
Adverse effects: bleeding
Do not require lab monitoring

Apixaban, edoxaban, rivaroxaban: directly inhibit factor Xa
Tx and prophylaxis for DVT and PE
Stroke prophylaxis for patients with AF
Adverse effects: bleeding
Oral agents that do not usually require lab monitoring
—
Anticoagulation reversal agents

Heparin: protamine sulfate: positively charged peptide that binds negatively charged heparin

Warfarin: vitamin K (slow), FFP or PCC (rapid)

Dabigatran: idarucizumab: monoclonal antibody Fab fragments

Direct factor Xa inhibitors: andexanet alfa: recombinant modified factor Xa

Question 32

Mode of action of tirofiban

Answer 32

Blocks GpIIb/GpIIIa (fibrinogen receptor) on activated platelets
———
Antiplatelets: decrease platelet aggregation

Aspirin: irreversibly blocks COX -> decreased TXA2 release
Used in ACS, coronary stenting
Decreased incidence or recurrence of thrombotic stroke
Adverse effects: gastric ulcers, tinnitus, allergic reactions, renal injury

Clopidogrel, prasugrel, ticagrelor, ticlodipine: block ADP (P2Y12) receptor -> decreased ADP-induced expression of GpIIb/IIIa
Used in dual antiplatelet therapy
Adverse effects: neutropenia (ticlodipine); TTP may be seen

Abciximab, eptifibatide, tirofiban: blocks GpIIb/GpIIIa (fibrinogen receptor) on activated platelets
Abciximab: made from monoclonal antibody Fab fragments
Used for unstable angina, PCI
Adverse effects: bleeding, thrombocytopenia

Cilostazol, dipyrimadole: blocks phosphodiesterase -> decreased cAMP in platelets
Used for intermittent claudication, stroke prevention, cardiac stress testing, prevention of coronary stent restenosis
Adverse effects: nausea, headache, facial flushing, hypotension, abdominal pain
—
Thrombolytics: alteplase, reteplase, streptokinase, tenecteplase
Directly or indirectly aid conversion of plasminogen to plasmin, which cleaves thrombin and fibrin clots
Increases PT, PTT, no change in platelet count
Used for early MI, early ischemic stroke, direct thrombolysis of severe PE
Adverse effects: bleeding
Contraindicated in patients with active bleeding, history of intracranial bleeding, recent surgery, known bleeding diatheses, or severe hypertension
Nonspecific reversal with antifibrinolytics (eg, aminocaproic acid, tranexamic acid), platelet transfusions, and factor corrections (eg, cryoprecipitate, FFP, PCC)

Question 33

All antitumor antibiotics are cell cycle nonspecific, except:

Answer 33

Bleomycin
——
Antibody drug conjugates: formed by linking monoclonal antibodies with cytotoxic chemotherapeutic drugs
Antibody selectivity against tumor antigens allows targeted drug delivery to tumor cells while sparing healthy cells -> increased efficacy and decreased toxicity
Ex: ado-trastuzumab emtansine (T-DM1) for HER2 ⊕ breast cancer
—
Antitumor antibiotics: all are cell cycle nonspecific, except bleomycin which is G2/M phase specific

Bleomycin: induces free radical formation -> breaks in DNA strands
Used for testicular cancer, Hodgkin lymphoma
Adverse effects: pulmonary fibrosis, skin hyperpigmentation

Dactinomycin (actinomycin D): intercalates into DNA, preventing RNA synthesis
Used for Wilms tumor, Ewing sarcoma, rhabdomyosarcoma
Adverse effects: myelosuppression

Anthracyclines (doxorubicin, daunorubicin): generate free radicals
Intercalate in DNA -> breaks in DNA
Inhibit topoisomerase II
Used for solid tumors, leukemias, lymphomas
Adverse effects: dilate cardiomyopathy (often irreversible; prevent with dexrazoxane), myelosuppression, alopecia

Question 34

A patient with sarcoma was treated with a folic acid analog. Which enzyme does this drug inhibit?

Answer 34

Dihydrofolate reductase
———
Antimetabolites: all S-phase specific except cladribine, which is cell cycle non specific

Thiopurines: azathioprine, 6-mercaptopurine
Purine (thiol) analogs -> decrease de novo purine synthesis
AZA is converted to 6-MP, which is then activated by HGPRT
Used for rheumatoid arthritis, IBD, SLE, ALL, steroid-refractory disease; prevention of organ rejection; weaning from steroids
Adverse effects: myelosuppression, GI and liver toxicity
6-MP inactivated by xanthine oxidase, so toxicity is increased with concomitant allopurinol or febuxostat use

Cladribine, pentostatin: purine analogs -> inhibit ADA, DNA strand breaks, etc.
Used for hairy cell leukemia
Adverse effects: myelosuppression

Cytarabine (arabinofuranosyl cytidine): pyrimidine analog -> DNA chain termination
Inhibits DNA polymerase
Used for leukemias (AML), lymphomas
Adverse effects: myelosuppression

5-FU: pyrimidine analog bioactivated to 5-FdUMP -> thymidylate synthase inhibition -> decreased dTMP -> decreased DNA synthesis
Capecitabine: prodrug
Used for colon CA, pancreatic CA, actinic keratosis, basal cell CA (topical)
Effects enhanced with addition of leucovorin
Adverse effects: myelosuppression, palmar-plantar erythrodyesthesia (hand-foot syndrome)

Hydroxyurea: inhibits ribonucleotide reductase -> decreases DNA synthesis
Used for myeloproliferative disorders (eg CML, PCV), sickle cell disease (increased HbF)
Adverse effects: severe myelosuppression, megaloblastic anemia

Methotrexate: folic acid analog that competitively inhibits dihydrofolate reductase -> decreased dTMP -> decreased DNA synthesis
Used for leukemias (ALL), lymphomas, choriocarcinomas, sarcoma
Also used for ectopic pregnancy, medical abortion (with misoprostol), rheumatoid arthritis, psoriasis, IBD, vasculitis
Adverse effects: myelosuppression (reversible with leucovorin “rescue”), hepatotoxicity, mucositis (eg mouth ulcers), pulmonary fibrosis, folate deficiency (teratogenic), nephrotoxicity

Question 35

Amifostine is given alongside cisplatin chemotherapy in order to prevent:

Answer 35

Fanconi syndrome
———
Alkylating agents: all cell cycle nonspecific

Busulfan: crosslinks DNA
Used to ablate patient’s bone marrow before bone marrow transplantation
Adverse effects: severe myelosuppression (in almost all cases), pulmonary fibrosis, hyperpigmentation

Nitrogen mustards (cyclophosphamide, ifosfamide): crosslink DNA, require bioactivation by liver
Used for solid tumors, leukemia, lymphomas, rheumatic disease (SLE, granulomatosis with polyangitiis)
Adverse effects: myelosuppression, SIADH, Fanconi syndrome (ifosfamide), hemorrhagic cystitis and bladder CA (prevent with MESNA)

Nitrosureas: cross link DNA
Requires bioactivation
Can cross BBB
Used for brain tumors (including glioblastoma multiforme)
Adverse effects: CNS toxicity (convulsions, dizziness, ataxia)

Procarbazine: weak MAO inhibitor
Used for Hodgkin, brain tumors
Adverse effects: bone marrow suppression, pulmonary toxicity, leukemia, disulfiram-like reaction
———
Platinum compounds: cisplatin, carboplatin, oxaliplatin
Cell cycle non specific
Crosslink DNA
Used for lymphomas, solid tumors eg bladder, testicular, ovarian, GI, lung
Adverse effects: nephrotoxicity (eg Fanconi syndrome, prevent with amifostine), peripheral neuropathy, ototoxicity
———
Microtubule inhibitors: M-phase specific

Taxanes (docetaxel, paclitaxel): hyperstabilize polymerized microtubules -> prevent mitotic spindle breakdown
Used for ovarian and breast CA
Adverse effects: myelosuppression, neuropathy, hypersensitivity

Vinca alkaloids: vincristine, vinblastine
Bind beta-tubulin and inhibit its polymerization into microtubules -> prevent mitotic spindle formation
Used for solid tumors, leukemias, Hodgkin, NHL
Adverse effects: vincristine: neurotoxicity (axonal neuropathy), constipation (including ileus)
Adverse effects: vinblastine: myelosuppression

Question 36

What is the target of the monoclonal antibody ipilimumab?

Answer 36

CTLA-4
———
Topoisomerase inhibitors: increase DNA degradation resulting in cell cycle arrest in S and G2 phases

Irinotecan, topotecan: inhibit topoisomerase I
Used for colon, ovarian, small cell lung CA
Adverse effects: severe myelosuppression, diarrhea

Etoposide, teniposide: inhibit topoisomerase II
Used for testicular CA, small cell lung CA, leukemias, lymphomas
Adverse effects: myelosuppression, alopecia
———
Tamoxifen: selective estrogen receptor modulator with complex mode of action: antagonist in breast tissue, partial agonist in endometrium and bone
Blocks binding of estrogen to ER in ER ⊕ cells
Used for prevention and treatment of breast cancer, prevention of gynecomastia in patients undergoing prostate cancer therapy
Adverse effects: hot flashes, increased risk of thromboembolic events (eg, DVT, PE), endometrial cancer
———
Anticancer monoclonal antibodies: work against extracellular targets to neutralize them, or promote immune system recognition

Alemtuzumab: targets CD52
Used for CLL, multiple sclerosis
Adverse effects: increased risk of infections and autoimmunity

Bevacizumab: targets VEGF (inhibits blood vessel formation)
Used for colorectal CA, RCC, NSCLC, angioproliferative retinopathy
Adverse effects: hemorrhage, blood clots, impaired wound healing

Cetuximab, panitumumab: targets EGFR
Used for metastatic CRC (wild-type RAS), head and neck CA
Adverse effects: rash, elevated LFTs, diarrhea

Rituximab: targets CD20
Used for NHL, CLL, rheumatoid arthritis, ITP, TTP, AIHA, multiple sclerosis
Increases risk of PML in patients with JC virus

Trastuzumab: targets HER2
Used for breast and gastric CA
Adverse effects: dilated cardiomyopathy (often reversible)

Pembrolizumab, nivolumab, cemiplimab: target PD-1
Used for various tumors eg NSCLC, RCC, melanoma, urothelial CA
Increases risk of autoimmunity eg dermatitis, enterocolitis, hepatitis, pneumonitis, endocrinopathies

Atezolizumab, durvalumab, avelumab: target PD-L1
Same clinical use and adverse effects as anti-PD-1

Ipilimumab: targets CTLA-4
Same clinical use and adverse effects as anti-PD-

Question 37

Molecular target of palbociclib

Answer 37

Cyclin dependent kinase 4/6
———
Anticancer small molecule inhibitors

Alectinib: targets ALK
Used for NSCLC
Adverse effects: rash, edema, diarrhea

Erlotinib, gefitinib, afatinib: target EGFR
Used for NSCLC
Adverse effects: rash, diarrhea

Imatinib, dasatinib, nilotinib: target BCR-ABL (also other tyrosine kinases eg c-KIT)
Used for CML, ALL, GISTs
Adverse effects: myelosuppression, increased LFTs, edema, myalgias

Ruxolitinib: targets JAK 1/2
Used for PCV
Adverse effects: bruises, increased LFTs

Bortezomib, ixazomib, carfilzomib: target proteasome (induce arrest at G2-M phase -> apoptosis)
Used for multiple myeloma, mantle cell lymphoma
Adverse effects: peripheral neuropathy, herpes zoster reactivation

Vemurafenib, encorafenib, dabrafenib: target BRAF
Used for melanoma
Often coadministered with MEK inhibitors (eg trametinib)
Adverse effects: rash, fatigue, nausea, diarrhea

Palbociclib: targets cyclin dependent kinase 4/6 (induces arrest at G1-S phase -> apoptosis)
Used for breast CA
Adverse effects: myelosuppression, pneumonitis

Olaparib: targets poly (ADP-ribose) polymerase -> decreases DNA repair
Used for breast, ovarian, pancreatic and prostate cancers
Adverse effects: myelosuppression, edema, diarrhea

Question 38

A patient noted chest pain and DOB after a few sessions of daunorubicin therapy. He was given a drug to ameliorate his symptoms. What is the mechanism of action of this drug?

Answer 38

Iron chelator
———
Amelioration of adverse effects of chemotherapy

Amifostine: free radical scavenger
Used for nephrotoxicity from platinum compounds

Dexrazoxane: iron chelator
Used for cardiotoxicity from anthracyclines

Leucovorin (folinic acid): tetrahydrofolate precursor
Used for myelosuppression from methotrexate (leucovorin “rescue”); also enhances the effects of 5-FU

Mesna: sulfhydryl compound that binds acrolein (toxic metabolite of cyclophosphamide/ifosfamide) Used for hemorrhagic cystitis from cyclophosphamide/ ifosfamide

Rasburicase: recombinant uricase that catalyzes metabolism of uric acid to allantoin
Used in tumor lysis syndrome

Ondansetron, granisetron: 5-HT3 receptor antagonists
Used for acute nausea and vomiting (usually within 1-2hr after chemotherapy)

Prochlorperazine, metoclopramide: D2 receptor antagonists
Used for acute nausea and vomiting (usually within 1-2hr after chemotherapy)

Aprepitant, fosaprepitant: NK1 receptor antagonists
Delayed nausea and vomiting (>24 hr after chemotherapy)

Filgrastim, sargramostim: recombinant G(M)-CSF
Used for neutropenia

Epoetin alfa: recombinant erythropoietin
Used for anemia

Question 39

Chemotoxicity of vincristine

Answer 39

Peripheral neuropathy
———
Key chemotoxicities

Cisplatin, Carboplatin: ototoxicity Vincristine: peripheral neuropathy Bleomycin, Busulfan: pulmonary fibrosis
Doxorubicin, Daunorubicin: cardiotoxicity
Trastuzumab: cardiotoxicity
Cisplatin, Carboplatin: nephrotoxicity
Cyclophosphamide: hemorrhagic cystitis

Nonspecific common toxicities of nearly all cytotoxic chemotherapies include myelosuppression (neutropenia, anemia, thrombocytopenia), GI toxicity (nausea, vomiting, mucositis), alopecia