Wk 11 - MC Questions on Hematology PDF

BMS 200 – Hematology 1 RBC Physiology and Iron-Deficiency Anemia Objectives Describe hematopoiesis and differentiation into red blood cells, white blood cells and platelets Describe erythropoiesis, red blood cell morphology and function, hemoglobin synthesis and function Describe the iron...

BMS 200 – Hematology 1 RBC Physiology and Iron-Deficiency Anemia Objectives Describe hematopoiesis and differentiation into red blood cells, white blood cells and platelets Describe erythropoiesis, red blood cell morphology and function, hemoglobin synthesis and function Describe the iron cycle in the context of erythropoiesis including iron absorption, transport, storage, excretion and regulation Describe the general mechanisms of iron deficiency, including common factors/situations that cause blood loss (including infectious causes like helminths and schistosomiasis), inadequate intake, increased demand for iron, and inadequate absorption of iron Red Blood Cells (Erythrocytes) An RBC, is a type of blood cell primarily responsible for carrying oxygen throughout the body. RBCs contain a protein called hemoglobin, which binds to oxygen in the lungs and releases it into tissues throughout the body. They also help in removing carbon dioxide, a waste product, by transporting it back to the lungs for exhalation. Red blood cells are produced in the bone marrow and have a lifespan of about 120 days before being recycled in the liver and spleen. Their unique biconcave shape allows them to move easily through blood vessels and maximize their surface area for efficient gas exchange.  Red Blood Cells (Erythrocytes) Major function of RBCs is gas transport & exchange ▪ Hemoglobin (Hb) binds reversibly to oxygen Hb binds to oxygen at high oxygen concentrations Oxygen dissociates from Hb at low oxygen concentrations When Hb is bound to oxygen, it is said to be saturated with oxygen ▪ In arterial blood Hb saturation is between 95% and 99% in healthy people ▪ RBCs are also important in transport of carbon dioxide Hb binds with a relatively low affinity to carbon dioxide RBCs also express the enzyme carbonic anhydrase Hemoglobin and the Hb Dissociation Curve RBCs and Carbon Dioxide We’ll discuss the physiology of gas transport in greater detail in BMS 250  Red Blood Cells (Erythrocytes) Adults produce RBCs in the bone marrow ▪ Proliferating marrow erythroid precursors + circulating RBCs = erythron ▪ RBCs are produced by the spleen and liver in the fetus Mature RBCs are small cells that do not have nuclei ▪ Therefore they are not able to synthesize protein – limits the lifespan of the RBC ▪ RBCs circulate for approximately 120 days (4 months) before being removed from the circulation, mostly by the spleen RBCs are small cells, with a bi-concave disc shape ▪ Diameter is ~ 7.5 microns ▪ Like a donut where the hole is not quite punched out… What would be the advantage(s) to this shape? A Normal Blood Smear Hematopoiesis and the RBC RBCs are derived from a myeloid progenitor (pronormoblast) Stimulated to divide by both GM- CSF (Granulocyte-Macrophage Colony-Stimulating Factor), which is a type of cytokine, which is a signaling protein and by erythropoietin (EPO) Prior to extrusion of the nucleus the RBC accumulates Hb and other essential proteins The late normoblast becomes anucleate The reticulocyte contains remnants of Golgi, ER, and ribosomes – they eventually extrude these and become mature RBCs Erythropoiesis The pronormoblast undergoes multiple cell divisions, resulting in the production of 16–32 mature red blood cells EPO stimulates division at the pronormoblast stage EPO is produced by the kidney by epithelial cells that line capillaries, near the tubules (peritubular) ▪ In conditions of high oxygen, HIF (hypoxia-inducible factor) is ubiquinated and degraded by proteasomes ▪ In conditions of low oxygen, HIF binds to other proteins, is translocated to the nucleus, and stimulates EPO production RBCs – general cellular physiology Generation of RBCs depends on: ▪ Adequate iron (and a.a.) for Hb production ▪ EPO ▪ A functional bone marrow RBCs do not rely on oxidative metabolism to generate ATP (solely glycolysis) ▪ No mitochondria RBCs have plentiful stores of glutathione ▪ Dealing with high concentrations of oxygen and no ability to synthesize new proteins = need to combat free radical production An array of cytoskeletal proteins ensure that the RBC can maintain its shape  FYI – RBC cytoskeletal proteins Inherited disorders can disrupt the cytoskeleton 🡪 loss of red cell mass (anemia)  Hemoglobin Each Hb molecule is made up of 4 subunits – two alpha chains and two “other” chains ▪ Each subunit has a heme moiety that contains iron – this is the site that binds oxygen Most adult Hb is known as Hb A – two alpha and two beta chains ( ~ 97%) ▪ Hb A is therefore α2β2 (97%) ▪ HbA2 uses delta chains instead (α2δ2) (2-3%) ▪ Very little fetal Hb is present in the healthy adult (α2γ2) – fetal Hb has a very high affinity for oxygen (why does this make sense?) Each RBC has about 250 million Hb molecules (900 g of Hb in an adult) Hemoglobin Many factors can impact the affinity of Hb for oxygen ▪ See graph in B – as the curve shifts to the right, that indicates a lower affinity for oxygen Fetal Hb has a very high affinity for oxygen because it cannot bind to 2,3 DPG well Carbon monoxide has a much higher affinity (200 X greater) for Hb than oxygen – forms carboxyhemoglobin Heme is produced through a complex set of reactions from glycine and succinyl-CoA as precursors Hemoglobin changes through the lifespan RBC formation and destruction Most RBCs are eliminated in the red pulp of the spleen by macrophages as they age and become more dysfunctional Hb has a complex metabolism ▪ iron is recycled and sent back to the bone marrow or stored (more later) ▪ Heme is eliminated in the bile and stool as bilirubin ▪ The “globin” (protein) is recycled into its component a.a. Liver – bilirubin conjugation review Senescent erythrocytes are phagocytosed by macrophages & heme will be degraded into biliverdin 🡪 bilirubin & released into the blood ▪ Unconjugated bilirubin carried to the liver bound to albumin In the liver bilirubin will be conjugated ▪ 1-2 residues of glucuronic acid are added ▪ Catalyzed by _________ Bilirubin glucuronide will be excreted into bile Kumar et. al., Robbins and Cotran Pathologic Basis of th Basic Iron Metabolism The body contains 3 – 4 g of iron – most is bound to Hb (2.5 g) Most iron is absorbed through the duodenal mucosa – heme iron is best absorbed, and reduced iron (Fe+2) is much better absorbed than Fe+3 ▪ Transported through the divalent metal transporter (DMT) ▪ Excess iron can accumulate and damage cells – the liver regulates the transport of iron from enterocytes into the bloodstream via a messenger known as hepcidin Hepcidin blocks the transporter ferroportin Iron is transported through the bloodstream via a transporter known as transferrin ▪ Transferrin “accepts” iron from ferroportin and has two binding sites (FYI – it carries oxidized iron Fe+3)  Basic Iron Metabolism Cells with transferrin receptors can endocytose transferrin and store it in a protein complex known as ferritin ▪ There is no method other than blood loss and shedding of intestinal epithelial cells for excretion of iron – therefore hepcidin production by the liver is important to prevent iron overload  Basic Iron Metabolism Major cells/tissues that store iron include the hepatocytes, the spleen, and the bone marrow ▪ Storage form of ferritin is known as hemosiderin These cells have the transferrin-1 receptor – transferrin is endocytosed (clathrin-coated pits via receptor-mediated endocytosis) and iron dissociates ▪ The transferrin receptor-transferrin complex is recycled back to the cell membrane  Basic Iron Metabolism Hepcidin production can be stimulated by pro-inflammatory cytokines (in particular, IL-6) Hepcidin production is inhibited by: ▪ Reduced iron stores in hepatocytes ▪ Erythroferrone – released by developing erythroblasts Small quantities of ferritin “leak” from hepatocytes and other cells into the serum ▪ Serum ferritin represents overall iron stores in the body Iron Deficiency Anemia (IDA) Globally, 50% of anemia is due to IDA ▪ Can be due to lack of iron in the diet or parasites that “steal” iron from the host ▪ Can be due to increased iron requirements due to physical activity, growth (i.e. childhood), and pregnancy ▪ Can also be due blood loss Menstruation Trauma Bleeding from the GI or GU tract – this can be caused by inflammation or malignancy, among other causes Blood loss > 10 – 20 mL of RBC/day cannot be compensated for by iron in a normal diet Iron Deficiency Anemia (IDA) North American iron intake: ▪ adult male is 15 mg/d with 6% absorption ▪ adult female is 11 mg/d with 12% absorption An individual with iron deficiency can increase iron absorption to ∼20% of the iron present in a meat- containing diet but only 5–10% of the iron in a vegetarian diet ▪ As a result, one-third of the female population in the United States has virtually no iron stores ▪ Vegetarians are at an additional disadvantage because certain foodstuffs that include phytates and phosphates reduce iron absorption by ∼50% IDA – Clinical & Diagnostic Features Symptoms: ▪ Fatigue, dyspnea, exercise intolerance ▪ Symptoms associated with blood loss Metrorrhagia Hematochezia, melena, hematuria Signs: ▪ Pallor (best observed in the conjunctiva, not a very reliable sign) ▪ Tachycardia ▪ Flow murmur – quiet, systolic murmur over the left precordium IDA – Clinical & Diagnostic Features Labs: ▪ CBC – abnormalities in the following RBC indices: Reduced RBC count and hematocrit (more about hematocrit later) Reduced Hb concentration Reduced reticulocytes (usually 0.5% - 2% of RBCs are reticulocytes) RBCs are small = microcytic RBCs have less hemoglobin = hypochromic ▪ Indicated by reduced mean cell hemoglobin concentration (MCHC) and mean cell hemoglobin (MCH) Increased red cell distribution width (RDW) – greater variation in RBC size  IDA – peripheral blood smear Severe iron- deficiency anemia. Microcytic and hypochromic red cells smaller than the nucleus of a lymphocyte associated with marked variation in size (anisocytosis) and shape (poikilocytosis). IDA – Clinical & Diagnostic Features Labs: ▪ Iron studies: Decreased ferritin Increased total iron binding capacity Decreased serum iron ▪ If IDA, can’t always assume that it’s due to inadequate iron intake In particular populations, possible causes of blood loss should also be investigated Iron stores Laboratory studies in the evolution of iron deficiency Measurements of marrow iron stores, serum ferritin, and total iron-binding capacity (TIBC) are sensitive to early iron-store depletion Iron-deficient erythropoiesis is recognized from additional abnormalities in the serum iron (SI) and percent transferrin saturation Progression of iron deficiency Initially, ferritin drops and TIBC increases Next, there is a drop in serum iron and transferrin saturation ▪ Although erythropoiesis is still occurring, this stage is known as iron-deficient erythropoiesis With continued iron deficiency one sees the CBC abnormalities of hypochromic, microcytic anemia ▪ A late sign of deficient iron stores Blood Hb concentrations fall and the peripheral smear looks more and more abnormal  Iron Deficiency Anemia - Etiologies You have a post- menopausal patient that eats meat most days and has what appears to be IDA based on labwork ▪ Other causes beyond nutritional? Absolute Iron Deficiency Definition: Reduction of total body iron stores, which may progress to IDA. Causes: Increased demand: Common in infants, preschool children, growth spurts in adolescents, and pregnancy. Decreased intake: Poverty, malnutrition, iron-poor vegan or vegetarian diets. Decreased absorption: Factors like dietary inhibitors, surgical procedures, certain medical conditions (e.g., Helicobacter pylori infection, coeliac disease), and use of proton-pump inhibitors. Chronic blood loss: Menstruation, frequent blood donation, infections like hookworm (helminths) and schistosomiasis, gastrointestinal bleeding, dialysis, and use of certain medications. Functional Iron Deficiency Definition: Iron is inadequately mobilized from stores to the circulation and erythropoietic tissue. Causes: Chronic inflammation and elevated hepcidin levels: Seen in chronic kidney disease, chronic heart failure, inflammatory bowel disease, chronic pulmonary diseases, cancer, obesity, autoimmune diseases, and chronic infections. Increased erythropoiesis: Resulting from endogenous erythropoietin responses to anemia or therapy with erythropoiesis-stimulating agents (ESA). Diagnostic Note: Indices of iron stores could be normal or high in these scenarios. BMS 200 - Hematology 2 Physiology of Hemostasis & Selected Disorders of Coagulation Outcomes Describe platelet morphology, platelet adhesion, aggregation, and platelet thrombus formation Describe platelet functions including coagulation and inflammation and infection Describe the steps of normal platelet plug formation including mediators and extracellular matrix constituents Describe the steps of normal fibrin clot formation including extrinsic and intrinsic pathways and the well-established relationship and interaction between activation of the coagulation cascade and acute inflammation Compare and contrast anti-thrombotic mechanisms (antithrombin vs. fibrinolysis) to normal physiology of hemostasis, and pathophysiology of hypercoagulation states and predict complications Compare and contrast between the pathophysiology of common inherited coagulation factor deficiencies--Hemophilia A: factor (F) VIII deficiency vs Hemophilia B: FIX deficiency Describe laboratory assessments of clotting factor deficiencies and appropriately apply use of prothrombin time (PT) and activated partial prothrombin time (aPTT) Describe the etiology and pathophysiology of acquired coagulation factor deficiencies including vitamin K deficiency, disseminated intravascular coagulation (DIC) and liver disease Hemostasis Hemostasis = process that prevents blood loss when a blood vessel is damaged Comprised of three major processes: ▪ Vasospasm and other vascular responses to injury ▪ Platelet activation and formation of a platelet plug ▪ Activation of the coagulation cascade and formation of fibrin One could consider hemostasis to include the process that prevents abnormal or excessive clot formation ▪ Extremely important as the coagulation cascade involves positive feedback loops  Overview image #1 FIGURE 31–11 - Summary of reactions involved in hemostasis Injury to a blood vessel exposes collagen and thromboplastin, recruiting platelets to the site of injury to form a temporary plug Platelets release 5- hydroxytryptamine, among other factors, resulting in smooth muscle contraction and vasoconstriction. Activation of the clotting cascade in response to collagen and thromboplastin activates thrombin, which converts circulating fibrinogen to fibrin monomers. Fibrin monomers polymerize and are cross-linked and accumulate with platelets at the site of injury to form the definitive clot. Overview Image #2 The coagulation cascade Note the two separate pathways: Extrinsic system – how the coagulation cascade is initiated and how the early fibrin plug is formed Intrinsic system – responsible for amplifying coagulation and forming a more stable fibrin plug Both pathways lead to a final common pathway The vessel wall and thrombosis Endothelial cells produce or express many antithrombotic factors: ▪ Prostacyclin (PGI2), nitric oxide, and ectoADPase/CD39 all inhibit platelet binding, secretion, and aggregation ▪ Endothelial cells produce anticoagulant factors Heparan proteoglycans, tissue-factor pathway inhibitor (TFPI), thrombomodulin ▪ Produce fibrinolytic enzymes Plasminogen activators The function of each of these will be discussed as we explore hemostasis – but it is key to remember that much of coagulation is regulated by the state of the endothelial cell Endothelial cell and thrombosis The endothelial cell plays a central role in the inhibition of various components of the clotting mechanism. Heparan sulfate proteoglycan potentiates the activation of antithrombin (AT) 15-fold. Thrombomodulin stimulates the activation of protein C by thrombin 30-fold HSPG = heparan sulfate proteoglycan; NO = nitric oxide; PAI- I = plasminogen activator inhibitor-I; PCI = protein C inhibitor; tPA = tissue plasminogen activator.  Platelets Produced/released by megakaryocytes in the bone marrow ▪ Regulated by thrombopoietin production (produced by the liver) Synthesis increased by inflammation (IL-6) and decreases in platelet number Anucleate cellular “fragments” that have a complex structure ▪ contain several mitochondria and a dynamic cytoskeleton ▪ many granules containing secretory elements and many receptors Approximately 1/3 of platelets are stored in the spleen, and can be released into the circulation during hemorrhage ▪ Lifespan of 7 – 10 days Platelets – key messengers and receptors “Granules” in platelets are pre-loaded vesicles or endosomes that are quickly released when platelets are activated ▪ Release is similar to exocytosis of neurotransmitters during synaptic transmission Two major types of granules ▪ Dense granules: contain small molecules, including: ADP – important activator of platelets when it binds to its extracellular receptor Calcium – key co-factor in Platelets – key messengers and receptors Two major types of granules: Alpha granules (most abundant) ▪ Von Willebrand factor (vWF) ▪ Factor V, fibrinogen and other coagulation factors ▪ Growth factors such as FGF, VEGF, and PDGF Also “stored” in alpha granules are important adhesive glycoproteins (see next slide) ▪ These transmembrane receptor-like glycoproteins are also expressed on Platelets – key messengers and receptors Platelet glycoproteins of note: GP Ib/IX – binds to vWF and is an early signal that results in the platelet release reaction GP Ia/IIa – binds to collagen under the endothelium – also an early signal that results in the platelet release reaction GPIIb/IIIa – a crucial GP in platelet function: ▪ Expressed in an inactive form on platelets that have not been stimulated  Platelet function – step-by-step Healthy vascular endothelium secretes nitric oxide, prostacyclin, and an ADPase (breaks down ADP) that prevents platelet activation A healthy vascular endothelium also “hides” collagen and vWF from circulating platelet GP receptors When the vascular endothelium is disrupted or activated: ▪ No secretion of anti- platelet mediators ▪ Exposure of collagen and vWF  Platelet function – step-by-step GP Ib/IX and Ia/IIa bind to either collagen and vWF 🡪 platelet adhesion to the vessel wall ▪ platelet release reaction (PlateRR) is triggered PlateRR 🡪 ▪ Rapid release of alpha and dense granules ▪ Conversion of GP IIb/IIIa to an activated state When GPIIb/IIIa binds to fibrinogen, platelets can now “stick” to each other 🡪 platelet aggregation  Platelet function – step-by-step The PlateRR leads to the release of a number of mediators that aid hemostasis: ▪ ADP – activates other platelets 🡪 PlateRR ▪ Serotonin – vasospasm ▪ Thromboxane A2 – vasospasm ▪ Coagulation factor release 🡪 increased production of fibrin and increased aggregation ▪ Calcium and poly- phosphate release 🡪 increased fibrin  Platelet function – step-by-step Platelets amplify coagulation by releasing TF vesicles and small procoagulant microparticles Platelets will also express P- selectin which will increase recruitment of leukocytes to a site of injury Platelets provide a phospholipid surface and a source of calcium which are both needed for the coagulation cascade to progress  Platelets and the coagulation cascade Note the importance of TF and a phospholipid surface in this diagram of both the intrinsic and the extrinsic pathways  The Coagulation Cascade Simplify before focusing on the details Extrinsic pathway: ▪ First to be activated ▪ Depends on Factor VIIa and TF (aka TPL or thromboplastin) ▪ Activates the final common pathway Intrinsic pathway ▪ Activated later, important for clot stabilization ▪ Depends on activating a sequence of many factors ▪ Also activates the final common pathway Final common pathway ▪ Factor Xa + Factor Va + Ca+2 ▪ Activates thrombin ▪ Also activates key components of the intrinsic pathway  The Extrinsic Pathway Physiologically, this is how coagulation is initiated (the intrinsic pathway is more slowly activated) Many cells outside the vasculature as well as activated platelets express a membrane protein called tissue factor (thromboplastin, factor III) ▪ When the integrity of the vessel is compromised, then FVII is exposed to tissue factor (TF) from cells in the underlying tissue 🡪 binding forming a FVIIa-TF complex This activates FX 🡪 FXa FXa will (inefficiently) activate prothrombin 🡪 thrombin and thrombin activates fibrinogen 🡪 fibrin The Intrinsic Pathway When FXII comes into contact with a negatively-charged surface (activated platelet membranes, basement membrane collagen, glass in a test tube) it becomes activated to FXIIa Usually occurs when complexed to high-molecular-weight kininogen (HMWK) – a protein expressed by activated platelets ▪ this production of FXIIa is slow, though Activated FXIIa converts pre-kallikrein in the serum to kallikrein ▪ HMWK anchors both FXII and pre-kallikrein in close proximity to each other ▪ Kallikrein converts more FXII 🡪 FXIIa (positive feedback) ▪ This allows more rapid conversion of FXII The Intrinsic Pathway Once there’s a bunch of HMWK-FXIIa around: The HMWK-FXIIa complex activates FXI 🡪 FXIa FXIa converts FIX 🡪 FIXa FIXa complexes with FVIIIa to activate FX 🡪 FXa ▪ FIXa-FVIIIa-Ca+2 complex is known as tenase And at this point FXa and FVa combine with serum calcium to activate prothrombin 🡪 thrombin ▪ FXa-FVa-calcium bound to a phospholipid surface is a very effective activator of prothrombin Cross-talk in Coagulation The extrinsic pathway produces a little bit of FIXa Thrombin will activate: ▪ FV 🡪 FVa ▪ FVIII 🡪 FVIIIa ▪ Also, thrombin can activate FXI as well as itself (prothrombin) – positive feedback Thrombin will also activate XIII 🡪 XIIIa ▪ XIIIa will cross-link fibrin strands leading to more stable clots being formed  Clotting and inflammation Factor XII also does a lot of pro-inflammatory stuff, either directly or indirectly ▪ It activates the kinin-kallikrein system, leading to the release of bradykinin Bradykinin acts like histamine, but lasts slightly longer It causes vasodilation, increased vascular permeability, pain, and smooth muscle contraction ▪ It leads to cleavage of C3 and C5 ▪ It leads to the production of thrombin and fibrin split products (clot leftovers), which both have pro- inflammatory effects Thrombin can cause chemokine, cyclooxygenase, and platelet-activating factor (PAF) production, which can cause the vasodilation, increased vascular permeability, and leukocyte emigration Clotting and inflammation BMS 200 - Hematology 2, part 2 Physiology of Hemostasis & Selected Disorders of Coagulation  Platelets and Inflammation Platelet plugs recruit leukocytes (neutrophils & monocytes) via P- selectin expression ▪ Platelets and leukocytes can interact in highly complex ways by modifying each others’ PG synthesis and impacting release of other pro-inflammatory mediators ▪ When leukocytes and platelets are allowed to interact, generation of thrombin is greater than if platelets alone are facilitating coagulation ▪ Platelet-leukocyte interactions likely optimize defence against microbes in the bloodstream Hemostasis – controlling clot formation Three major general mechanisms are used to decrease clot formation: ▪ Downregulation of platelet activation Prostacyclin, NO production are main mechanisms ▪ Downregulation of the coagulation cascade Very important mechanism of decreasing coagulation ▪ Destruction of fibrin clots (fibrinolysis) Very important mechanism of decreasing coagulation Pharmacotherapeutics are available that increase all these processes  Recall – how is platelet activation inhibited? Healthy vascular endothelium secretes nitric oxide, prostacyclin, and an ADPase (breaks down ADP) that prevents platelet activation Nitric oxide and prostacyclin both inhibit the PlateRR How would an ADPase inhibit the PlateRR? Down-regulation of coagulation cascade Known as antithrombotic or anticoagulation mechanisms Antithrombin inhibits thrombin and activated factors IX, X, XI, and XII ▪ Heparin expressed on endothelial cells increases the activity of antithrombin, which occurs physiologically on vascular surfaces Protein C is activated by thrombin ▪ Activated protein C and protein S form a complex that binds to an endothelial surface protein known as thrombomodulin ▪ Activated protein C/S cleaves Va and VIIIa In the presence of heparin, tissue factor pathway inhibitor (TFPI) is released – it inhibits the activation of thrombin by TF and FVIIa Anticoagulant and fibrinolytic mechanisms Fibrinolytic system When appropriate (healthy endothelium), endothelial cells release tissue plasminogen activator (tPA), which activates plasminogen 🡪 plasmin ▪ Plasmin is then able to degrade fibrin – plasmin only works at sites where fibrin has been deposited (not circulating fibrin) ▪ Fibrin that has been crosslinked (which factor) then produces what are known as D- dimers (or fibrin degradation products) as a product of fibrin proteolysis Plasminogen activator inhibitors (PAIs) block the activity of tPA, and alpha-2 antiplasmin binds to plasmin ▪ There is also a thrombin-activated fibrinolysis inhibitor that inhibits fibrinoloysis  Laboratory Tests of Coagulation Basic tests listed here – more complex, specific tests can be requisitioned by a hematologist ▪ Prothrombin time – PT Labs will differ in terms of how they report the PT, so it is normalized to a particular standard – known as the international normalized ratio (INR) Reflects the time it takes to form a clot via the extrinsic coagulation cascade, not the intrinsic ▪ Thromboplastin is placed in the blood sample and time to clot is measured ▪ Activated partial thromboplastin time - aPTT Reflects the time it takes to form a clot via the intrinsic coagulation cascade, not extrinsic Phospholipids are placed in the blood sample, and time to clot is measured ▪ Thrombin time – thrombin added, tests for the presence/activity of fibrinogen ▪ Platelet count – literally, just counting the number of platelets/microlitre  Lab testing and coagulation function FIGURE 116-1 Coagulation cascade and laboratory assessment of clotting factor deficiency by activated partial prothrombin time (aPTT), prothrombin time (PT), thrombin time (TT), and phospholipid (PL). Hemophilia A and B Hemophilia A is a deficiency in FVIII; Hemophilia B is a deficiency in FIX ▪ Both are on the X-chromosome – so X-linked recessive disorders What group is the most likely to express these disorders? FVIII is a larger gene, so more chance for the development of mutations – modern sequencing can predict severity of bleeding disorder based on type of mutation ▪ Uncommon – hemophilia A is 1 in 5000 prevalence, hemophilia B is 1 in 30,000 However, these are the most common inherited deficiencies in coagulation, other than von Willebrand’s disease (more next class) Hemophilia A and B Hemophilias have essentially the same clinical presentation ▪ The majority have defects in coagulation labs that are discovered incidentally < 1% have severe hemophilia, 1-5% have moderate, 6 – 30 % have mild hemophilia ▪ Hemophilias present differently depending on severity: Severe – spontaneous “deep” bleeds such as into joints soft tissues, and muscles with very minor trauma or spontaneously ▪ Hemarthroses are painful and will limit movement as well as cause damage to the joint ▪ Sometimes intracranial bleeds (can be catastrophic) Milder disease presents with few episodes of deep bleeds and prolonged bleeding with mild trauma or with dental procedures or epistaxis Hematuria can occur with all types of hemophilia Hematology 3 Anemias - P2 Outcomes Describe etiology, pathophysiology, clinical presentation, and laboratory assessments of anemia due to acute and chronic inflammation Describe etiology, pathophysiology and relate to laboratory assessments and conventional treatment (brief) of Inherited Hemolytic Anemias due to Abnormalities of the Membrane-Cytoskeleton including hereditary spherocytosis Describe etiology, pathophysiology and relate to laboratory assessments of inherited hemolytic anemias due to abnormalities of hemoglobin including sickle cell and alpha and beta thalassemia Describe etiology, pathophysiology, and relate to laboratory assessments of inherited hemolytic anemias due to abnormalities of the metabolic enzymes such as G6PD deficiency Describe infectious causes of hemolytic anemias including malaria and Babesia microti Anemias of Inflammation (AI) Thought to be one of the more common anemias seen clinically (second to IDA according to some sources) ▪ this likely applies to “sicker” populations that are hospitalized – less common in a general practice setting, though it is still very common ▪ More common in the elderly population Laboratory investigation of microcytic anemia is often focused on differentiating between IDA and AI ▪ Present similarly and have similar findings on CBC ▪ Iron handling is quite different What are the major causes of AI? ▪ Chronic infection (i.e. tuberculosis or HIV) ▪ Autoimmune conditions – in particular rheumatoid arthritis or lupus ▪ Inflammatory bowel disease (CD and UC) ▪ Many malignancies Pathogenesis – AI A variety of inflammatory cytokines suppress erythropoiesis Due to reduced erythropoietin production Due to iron sequestration Due to direct effects on early myeloid progenitors FIGURE 97-4 Suppression of erythropoiesis by inflammatory Acute infection can also lead to cytokines. Through the release of tumor necrosis premature destruction of factor (TNF) and interferon β (IFN-β), neoplasms “older” RBCs and bacterial infections suppress erythropoietin This typically causes small (EPO) production and the proliferation of decreases in [Hb] erythroid progenitors (erythroid burst-forming units and erythroid colony-forming units [BFU/CFU-E]). The mediators in patients with Pathogenesis – AI Suppression of EPO release – IL-1 and TNF-alpha Suppression of RBC precursors – IFNs ▪ IFN release is also Sequestration stimulated by“away” of iron TNF- from the bone marrow ▪ IL-1 alphaandand TNF-alpha IL-1 will both stimulate the release of IL-6 ▪ IL-6 increases the production of hepcidin 🡪 reduced availability of iron for hematopoiesis (see next slide) With age, EPO production declines and may be normal with minor or modest decreases in Hb concentration Hepcidin does the following: Decreases absorption from the intestine (traps iron in the intestinal epithelium) Decreases the transfer of iron from transferrin to hepatocytes Decreases liberation of iron from the AI – Clinical Features Often the symptoms of AI are mostly due to the underlying disease ▪ A key part of the treatment of AI is treatment of the underlying disease ▪ Most malignant, chronic infectious, and autoimmune disorders prominently feature fatigue Many of the disorders that cause AI can also be associated with blood loss, so a mixed picture can occur ▪ Suspect AI when iron supplementation/correction of bleeding does not resolve the anemia Anemia of Chronic Kidney Disease CKD can cause moderate – severe hypoproliferative anemia ▪ Worsens with more advanced stages of CKD ▪ Mostly due to decreased EPO and poorly-characterized reductions in RBC survival RBCs are usually normocytic + normochromic ▪ Reticulocyte counts are decreased EPO can treat the anemia, however many of the symptoms of CKD that are similar to those of anemia (fatigue, exercise intolerance) are due to the underlying renal dysfunction (more in BMS 250) Laboratory Features – Hypoproliferative Anemias Iron stores - recall Laboratory studies in the evolution of iron deficiency Measurements of marrow iron stores, serum ferritin, and total iron-binding capacity (TIBC) are sensitive to early iron-store depletion Iron-deficient erythropoiesis is recognized from additional abnormalities in the serum iron (SI) and percent transferrin saturation Anemias of Abnormal RBC Synthesis Abnormal Hb synthesis: Sickle cell anemia Thalassemia ▪ Alpha & beta thalassemia Genetic metabolic or cytoskeletal disorders G-6-PD deficiency Hereditary spherocytosis Hereditary Spherocytosis Most common type of anemia due to defects in cytoskeletal elements ▪ 1:2000 – 1:5000 in those of European heritage Hereditary spherocytosis is not caused by one particular gene, and there are closely related disorders (hereditary elliptocytosis, hereditary stromatocytosis) that can be caused by genetic defects in associated cytoskeletal proteins Most common causes of hereditary spherocytosis include the following mutations: ▪ Autosomal dominant mutation in ankyrin ▪ Autosomal dominant mutations in the anion exchanger 1 (AE1) RBC membrane & cytoskeleton Ankyrin “anchors” spectrin and actin to the cell membrane Band 3 is also known as the AE 1 ▪ a very rapid anion exchanger involved in fluid exchange across the RBC membrane and RBC volume homeostasis ▪ Also associated with the protein complex that anchors the cytoskeleton to the membrane  Hereditary Spherocytosis Presents with variable severity of clinical features Severe: severe anemia in early life that may need transfusions and results in splenomegaly, jaundice, and a greatly enlarged spleen Mild: presents later in life with gallstones, splenomegaly, and jaundice (often episodic) ▪ Most cases are mild-moderate Anemia is normocytic with an increased RDW and increased MCHC ▪ Spherocytes are poorly deformable, therefore they are sequestered and destroyed earlier than normal in the spleen G-6-PD deficiency G6PD is absolutely necessary in RBCs – only source of NADPH and the only method of reducing glutathione (see next two slides) ▪ About 500 million people have a gene that is deficient in activity ▪ Likely somewhat protective against the development of malaria Symptoms/signs usually arise in situations where RBCs are exposed to some sort of oxidative stress ▪ Medications (a variety of antibiotics, aspirin) ▪ “Intravascular” inflammation – activation of neutrophils in blood vessels ▪ Foods – fava beans in particular (contain a glucoside known as divicine that increases free radical production) G-6-PD deficiency – global prevalence RBC metabolism FIGURE 100-1 Red blood cell (RBC) metabolism. The Embden-Meyerhof pathway (glycolysis) generates ATP required for cation transport and for membrane maintenance The generation of NADH maintains hemoglobin iron in a reduced state. The hexose monophosphate shunt generates NADPH that is used to reduce glutathione, which protects the red cell against oxidant stress; the 6- phosphogluconate, after decarboxylation, can be recycled via pentose sugars to glycolysis. Regulation of the 2,3-  G-6-PD deficiency In G6PD-normal red cells, G6PD and 6-phosphogluconate dehydrogenase provide ample supply of NADPH, which in turn regenerates GSH when this is oxidized by reactive oxygen species (e.g., O2– and H2O2). In G6PD-deficient red cells, where the enzyme activity is reduced, NADPH production is limited, and it may not be sufficient to cope with the excess ROS generated by pro- oxidant compounds, and the consequent excess hydrogen peroxide.  G-6-PD – Pathogenesis & Clinical Features Genetic – X-linked disorder ▪ More likely to be expressed in men Clinical Features: ▪ Hemolytic anemia precipitated by oxidative insults to RBCs ▪ An attack tends to involve: Malaise, weakness, abdominal/back pain early In the next 2-3 days, jaundice and hyperbilirubinuria/unconjugated hyperbilirubinemia Moderate – severe anemia ▪ Reduction in Hb, anisocytosis, spherocytes, “bite cells” Elevation in LDH and reduction in haptoglobin ▪ LDH – lactate dehydrogenase, released with RBC rupture ▪ Haptoglobin – a free heme/iron “scavenger” that is produced by the liver Peripheral smear in G-6-PD attack Peripheral blood smear from a glucose-6-phosphate dehydrogenase (G6PD)-deficient boy experiencing hemolysis. Note the red cells that are misshapen and called “bite” cells. Thalassemias Caused by mutations that reduce the synthesis of adult hemoglobin – HbA (HbA, alpha and beta chains, usually 97% of Hb) ▪ Fetal hemoglobin (HbF, alpha and gamma chains, usually none in adults), HbA2 (alpha and delta chains, usually 3% of adult Hb) Can be caused by mutations that lead to absent beta-globin chains or reduced beta-globin chains (chromosome 11, one copy each chromosome) ▪ Beta globin tends to be absent with nonsense mutations ▪ Beta globin is reduced with mutations that affect splicing out of introns and promoter regions Less commonly caused by absent alpha-globin ▪ 4 copies – 2 on each of chromosome 16 Common in: Mediterranean basin, Middle East, tropical Africa, India, Asia ▪ Carrier rate ranges from 3 – 18% Beta thalassemias Production of red cells with reduced hemoglobin As well, with a deficiency of beta chains, alpha chains can precipitate, leading to abnormalities of erythrocyte shape ▪ Damages red cell membranes ▪ Abnormal erythrocytes are removed from the circulation by phagocytes Therefore a combination of poor RBC production (ineffective erythropoiesis) and increased RBC destruction (hemolysis) Beta thalassemias Other pathophysiologic events include: ▪ Bony abnormalities due to marrow expansion as the marrow tries to “keep up” red cell production ▪ Extramedullary hematopoiesis in spleen and liver, causing their enlargement ▪ Repeat transfusions and increased iron absorption can lead to iron overload (heart and liver damage) a type of secondary hemochromatosis (excessive iron levels leading to iron deposition in widespread areas of the body) Pathogenesis of beta-thalassemia major Blood transfusions are a double-edged sword, diminishing the anemia and its attendant complications, but also adding to the systemic iron overload. Name Description of Beta-thalassemia Alleles Only one of β globin alleles bears a mutation. Individual will suffer microcytic Thalassemia anemia. Detection usually involves lower than normal MCV value (3.5%) and a decrease in fraction of β+/β or βo/β Hemoglobin A (30,000 daughter merozoites 3. These few swollen infected liver cells eventually burst, discharging motile merozoites into the bloodstream 4. The merozoites then invade red blood cells (RBCs) to become trophozoites ▪ in the non-immune, multiply up to twentyfold every 48 h 5. When the parasites reach densities of ~50/μL of blood, the symptomatic stage of the infection begins  Malarial Life Cycle FIGURE 224-1 The malaria transmission cycle from mosquito to human and targets of immunity. In P. vivax and P. ovale infections some liver stage parasites remain dormant (“hypnozoites”), and awake weeks or months later to cause relapses. RBC, red blood cell. Most common and severe malarial parasite – P. falciparum Malarial Life Cycle P. falciparum invades rapidly and does not remain dormant in the liver – symptoms occur soon after initial inoculation, and relapses do not occur ▪ In P. vivax and P. ovale infections, a proportion of the intrahepatic forms do not divide immediately but remain inert for a period ranging from 2 weeks to ≥1 year – relapses can occur Malaria attaches to and invades RBCs through complex interactions with a variety of RBC membrane proteins ▪ By the end of the intraerythrocytic life cycle, the parasite has consumed two-thirds of the RBC’s Malarial Life Cycle The disease in human beings is caused by the direct effects of the asexual parasite—RBC invasion and destruction—and by the host’s reaction. ▪ Some of the blood-stage parasites develop into morphologically distinct, longer-lived sexual forms (gametocytes) that can transmit malaria ▪ These gametocytes will reproduce in a mosquito’s gut during another blood meal… and the sporocytes can again be transmitted to another person Malaria and the host Malaria induces RBCs to express a parasitic protein on their membrane – PfEMP1 ▪ Mediates attachment of RBCs to receptors on the capillary and the venule endothelium (multiple endothelial proteins can act as receptors) ▪ As the parasite matures, RBCs get stuck in and eventually block a variety of capillaries and venules throughout the body Aggregation can interfere with blood flow in the brain in particular, and sequestered RBCs can’t be removed by the spleen if they’re stuck Malaria – Clinical Features Milder forms – mortality of less than 0.1% Fever, often severe Headache, abdominal pain, muscle aches are all common ▪ Pain is not usually particularly severe (compared to other infectious illnesses) Severe forms Tend to occur when parasite infestation exceeds 2% of erythrocytes – see table next slide Severe malarial complications  Selected Features of Severe Malaria Cerebral malaria – can cause coma, obtundation, or delirium ▪ Retinal hemorrhages and papilledema may also be seen, no neck stiffness (no meningitis), seizures can occur ▪ Death rates of up to 20% ▪ 10% of children that survive cerebral malaria suffer permanent neurologic deficits (language deficits common) Dangerous hypoglycemia from impaired gluconeogenesis and consumption of glucose by host and parasites Severe acidosis and non-cardiogenic pulmonary edema  Peripheral smear - malaria FIGURE 224-5 Thin blood films of Plasmodium vivax. A. Young trophozoite. B. Old trophozoite. C. Mature schizont. D. Female gametocyte. E. Male gametocyte. (Reproduced from Bench Aids for the Diagnosis of Malaria Infections, 2nd ed, with the permission of the World Health Part II – Leukemias and Lymphomas – an Introduction Objectives Describe etiology, pathophysiology and relate to clinical presentation and laboratory assessments of Acute Lymphoid Leukemia Describe etiology, pathophysiology and relate to clinical presentation and laboratory assessments of Chronic Lymphocytic Leukemia Describe etiology, pathophysiology and relate to clinical presentation and laboratory assessments of Non-Hodgkin's Lymphoma (specifically follicular and diffuse) Describe etiology, pathophysiology and relate to clinical presentation and laboratory assessments of Hodgkin's Lymphoma Describe etiology, pathophysiology and relate to clinical presentation and laboratory assessments of Acute Myeloid Leukemia Describe etiology, pathophysiology, clinical presentation, laboratory assessments of Chronic Myeloid Leukemia Neoplasms of blood cells Lymphoid neoplasms: ▪ Hodgkin’s lymphoma ▪ non-Hodgkin’s lymphoma (NHL) ▪ Lymphocytic leukemias Myeloid neoplasms – for next day ▪ Acute myelogenous leukemias ▪ Chronic myeloproliferative disorders Neoplasms of blood cells Leukemia: ▪ Tumours that primarily involve overgrowth of cells in the bone marrow ▪ Eventually 🡪 bone marrow suppression, immature cells in the peripheral blood smear Lymphoma: ▪ Presents as a mass in lymphatic tissue, and less frequently in other solid organs ▪ Can eventually invade bone marrow Can overlap in clinical presentation – thus most helpful to know type of cells in the tumour, not where the tumour resides Acute lymphoblastic leukemia/lymphoma. Lymphoblasts with condensed nuclear chromatin, small nucleoli, and scant agranular cytoplasm. Acute myeloid leukemia without maturation Myeloblasts have delicate nuclear chromatin, prominent nucleoli, and fine Lymphoid neoplasms Most are B-cell precursors ▪ Seems that malignancy develops during: Antibody class switching Recombination events to increase antibody affinity Almost always monoclonal ▪ Tumours arise from a single malignant clone Non-Hodgkin lymphoma (NHL) tends to be more widespread at diagnosis Hodgkin lymphoma tends to be localized and travel predictably along lymph nodes General Principles – lymphoid neoplasms Leukemias and lymphomas can have variable and overlapping clinical presentations, however: ▪ Leukemias usually first present with signs of a) pancytopenia b) some malignant cells in a peripheral blood smear Later lymph node enlargement and invasion of skin or CNS can occur ▪ 100% of Hodgkin’s lymphoma and about 2/3 of NHL first present with enlarged lymph nodes (the other 1/3 of NHL often presents with solid organ infiltration) Later, bone marrow involvement can result in pancytopenia White cell malignancies – general pathogenesis Chronic inflammation – some chronic inflammatory conditions result in constant lymphocytic mitosis and predispose to lymphoma ▪ Celiac disease, Chronic gastritis Viral infection ▪ EBV – associated with Burkitt lymphoma, Hodgkin lymphoma, many NHLs, some NK malignancies ▪ HHV-8 – rare B-cell lymphoma ▪ HTLV-1 – adult T-cell lymphoma/leukemia ▪ HIV – NHLs White cell malignancies – general pathogenesis Most lymphocytic malignancies are B-cell neoplasms ▪ B-cells are more vulnerable to malignant change due to antibody rearrangement Enzymes (AID = activation-induced cytosine deaminase and recombinases/RAGs) create breaks in antibody genes for: ▪ Class switching (mostly AID) ▪ Hypermutation to aid antibody affinity (mostly recombinases but also AID) ▪ Can cause chromosomal translocations 🡪 decreased apoptosis, increased growth, or both  White cell malignancies – general pathogenesis Increased cell division: ▪ MYC, receptor tyrosine kinase mutations, Ras and downstream signallers (MAPK and PI-3K signalling) Disruptions in apoptotic pathways Mutations that halt normal differentiation ▪ If there’s an arrest at differentiation when a cell population is dividing rapidly, this can predispose to cancer Many of these genetic defects are due to chromosomal translocations Remember – B-cells mutate themselves all the time “on purpose” ▪ Activation of AID, class switching, somatic hypermutation Age and Leukemia Acute lymphoblastic leukemia Arises from precursor B-cells and precursor T-cells ▪ Similar clinical picture to acute myelogenous leukemia (myeloid cell precursors), however has a different response to treatment ▪ 80% of all childhood leukemias – most common cancer of children Immature leukemic blast cells are “blocked” in differentiation ▪ Requires < 10 mutations to develop ALL (genetically “simple”) ▪ As immature, non-functional blast cells accumulate: They “crowd” out normal cells and bone marrow failure occurs Encourage self-renewal in the bone marrow Acute lymphoblastic leukemia Clinical features: ▪ 85% are derived from precursor B-cells ▪ Abrupt onset – days to a few weeks of symptom development: Fatigue Infection – neutropenia (often present with fever) Bleeding (easy bruising, nose bleeds, gum bleeding) ▪ Bone pain and tenderness can occur from marrow expansion and invasion of bone ▪ Solid organs that are affected by metastases: Spleen, liver, testes, lymph nodes, meninges ▪ T-cell derived ALLs have very similar clinical behaviour, although they Involve different mutations Involve different age groups Acute lymphoblastic leukemia Clinical features ▪ Generalized lymphadenopathy, splenomegaly, and hepatomegaly ▪ Central nervous system involvement Cranial nerve palsies Headache Vomiting Involvement of solid organs is rare in acute myelogenous leukemia, but common in ALL ▪ Otherwise they present very similarly Acute lymphoblastic leukemia Diagnosis ▪ Depends on presence of blast cells found in bone marrow and peripheral blood smears Absence of blast cells in a significant number of patients on peripheral smear Depends on bone marrow aspiration for diagnosis ▪ White cell count can be elevated or depressed depressed due to generalized marrow failure ▪ Identification depends on finding certain chromosomal abnormalities and overexpression of some enzymes Hyperdiploidy (> 50 chromosomes/cell) present in 90% Acute lymphoblastic leukemia Prognosis/treatment ▪ Children ages 2 – 10 tend to do very well with treatment Younger children are more likely to have malignant cells that began B- cell differentiation, older children more likely to have a “T-cell precursor” leukemia ▪ 95% attain remission, 75% - 85% are cured ▪ Adults and older children have a worse prognosis – 35% - 40% cure rate ▪ Despite good cure and remission rates, leading cause of cancer death in children Chronic lymphocytic leukemia Basically same disease as small lymphocytic lymphoma – arbitrarily defined as one or the other based on number of lymphocytes found in peripheral blood ▪ Only about 4% of NHLs are classified as small lymphocytic lymphoma Most common leukemia of adults in Western world (very uncommon in Asia) ▪ Close to 20,000 new cases every year in North America CLL - Pathogenesis Tumour of relatively mature B-cells, expressing CD 19, CD 20, and CD 23 ▪ Thought to be derived from a mutation in memory cells Although this malignancy seems to be familial, no candidate genes have been clearly identified ▪ Genes that are implicated include apoptosis-related genes, genes that affect telomeres, and BCR genes Tumour cells seem to depress normal B-cell function; oddly, they will sometimes induce autoantibodies in normal B-cells as well ▪ Hypogammaglobulinemia ▪ Deficient T-cell responses Chronic lymphocytic leukemia Clinical features ▪ Often asymptomatic Often diagnosed based on an elevated lymphocyte count ▪ Most common symptoms are weight loss, fatigue, and anorexia ▪ Lymphadenopathy or splenomegaly are found in the majority of cases ▪ Susceptibility to bacterial infection is common and a leading cause of death As well, hemolytic anemia and thrombocytopenia due to autoantibody production Chronic lymphocytic leukemia Prognosis/treatment: ▪ Tends to be a slow-growing tumour – most people live more than 10 years after diagnosis, and die from unrelated causes Usually sets in later in life ▪ It can transform into more aggressive tumours; if it does, survival tends to be less than one year tends to transform to a large-cell, diffuse B-cell lymphoma  Non-Hodgkin’s Lymphoma Cancers of mature B, T, and NK cells. Divided into mature B-NHL and mature T/NK-NHL B-cell NHL is by far the most common Non-Hodgkin’s Lymphoma Risk factors: Agricultural chemical exposure Treatment for Hodgkin’s lymphoma (HL), unclear if consequence of HL or its treatment. Epstein-Barr virus (EBV), HIV infection, H. pylori infection, Hepatitis C virus infection, Human herpesvirus 8 Immunosuppression (iatrogenic, AIDS, autoimmune diseases) increases NHL risk, often associated with EBV. Diseases of inherited and acquired immunodeficiency, autoimmune diseases linked to higher lymphoma incidence Increased NHL risk observed in first-degree relatives with NHL, HL, or chronic lymphocytic leukemia (CLL). Non-Hodgkin’s Lymphoma About 90% of all lymphomas are of B cell origin. ▪ Common mutations in B-cell lymphomas involve transcription factors MYC and BCL6, and antiapoptotic protein BCL2. Non-Hodgkin’s Lymphoma - Diffuse Large B-Cell Lymphoma Most common NHL subtype; ~ one-third of all cases. Median age at diagnosis is 64 Rapid and aggressive growth, and it often presents at an advanced stage. Risk factors: first degree relative with DLBCL, immunodeficiency, immunosuppression, autoimmune disorders (often EBV-related). Majority present with advanced-stage disease 40% have "B" symptoms fever, night sweats, weight loss ▪ 50% have elevated LDH Extranodal involvement: bone marrow, CNS, gastrointestinal tract, thyroid, liver, skin Extensive bone marrow involvement or involvement of specific sites increases risk of CNS dissemination  Non-Hodgkin’s Lymphoma - Diffuse Large B-Cell Lymphoma Diffuse proliferation of large, atypical lymphocytes with high proliferative index Genetic alterations: BCL2 loss of function (anti-apoptotic BH4 signal) BCL6+ (transcripition factor for follicular helper T-cells) MYC rearrangements in 10% “double-hit lymphoma” (MYC, BCL2, and/or BCL6) has poor prognosis Non-Hodgkin’s Lymphoma – Follicular Lymphoma - FYI Diagnosed based on morphological & immunohistochemical findings. Confirmation of B-cell immunophenotype (positive for CD19, CD20, CD10, BCL6; negative for CD5 and CD23) the presence of t(14;18) translocation, and abnormal expression of BCL2 protein are confirmatory. FL is characterized by small cleaved and large cells organized in a follicular pattern of growth. FL is graded from I to III based on the number of centroblasts (large cells) counted per high-power field. Grades I and II have lower numbers of centroblasts Higher grades mean more invasive disease  Non-Hodgkin’s Lymphoma – Follicular Lymphoma The most common presentation is painless lymphadenopathy, often involving multiple sites. Unusual sites such as epitrochlear nodes can be affected. Extranodal involvement is possible, and any organ may be affected. Staging/diagnosis – CT, PET/CT imaging ▪ Prognosis is best predicted by the Follicular Lymphoma International Prognostic Index (FLIPI). Hogkin’s Lymphoma Primarily affects mature B lymphocytes, representing approximately 10% of all diagnosed lymphomas annually. Two main subtypes: classical Hodgkin's lymphoma (cHL) and nodular lymphocyte-predominant Hodgkin's lymphoma (NLPHL). ▪ NLPHL resembles cHL morphologically in certain aspects, but there is evidence suggesting that it is more related to indolent B-cell non-Hodgkin's lymphomas (NHLs) biologically. cHL subtypes (FYI): ▪ Nodular Sclerosis ▪ Mixed Cellularity ▪ Lymphocyte-Rich  Hogkin’s Lymphoma Likely association between EBV infxn and HL 20-40% of HL patients have a monoclonal or oligoclonal proliferation of EBV-infected cells HIV is a risk factor for cHL nearly all cases of HIV-associated cHL show evidence of Epstein-Barr virus (EBV) infection Reed-Sternberg (HRS) Cells - large cells with abundant cytoplasm and bilobed/multiple nuclei (owl’s eye cells) ▪ Diagnostic of cHL. express the EBV-transforming protein latent membrane protein 1 (LMP-1) Almost all express PD-1 ligand Allows immune evasion from cytotoxic T- cells, expressed by many cancers Hogkin’s Lymphoma Clinical Features: Most patients present with palpable, nontender lymphadenopathy ▪ Earlier in the course found in cervical, supraclavicular, and axillary lymph nodes. ▪ Mediastinal lymphadenopathy is common, and in some cases, it can be the initial manifestation. ▪ Subdiaphragmatic presentation is unusual, but common in older males. Represents progression of the disease in most About one-third of patients present with "B" symptoms, which include fevers, night sweats, and weight loss. Wide range of other atypical presentations ▪ FYI - include severe itching, cutaneous disorders, paraneoplastic cerebellar degeneration or other CNS effects, nephrotic syndrome, immune hemolytic anemia and thrombocytopenia, hypercalcemia, lymph node pain with alcohol ingestion.  Hogkin’s Lymphoma Laboratory Evaluation: ▪ CBC with diff (more next class), erythrocyte sedimentation rate (ESR) ▪ Hepatic & renal labs, HIV and hepatitis testing Imaging: ▪ Positron emission tomography (PET)/computed tomography (CT) scan is used for staging & diagnosis