USMLE Step 2 (Fach) / Hematology/Oncology (Lektion)
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Step 2 CK
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- Normal hemostasis Vascular injury leads to the release of vWF and tissue factor from subendothelial vessel walls.- vWF facilitates attachment and aggregation of platelets, forming a platelet plug- Tissue factor triggers ...
- Hemophilia X-linked clotting factor deficiencies of factors VIII (hemophilia A, 80% of cases), factors IX (hemophilia B), and XI (hemophilia C) that result in an ↑ tendency to bleed. Rarely, hemophilias can be ...
- Heparin Mechanism: Activates antithrombin Lab values: ↑ PTT Antidote is protamine sulfate.LMWH has more effect on factor Xa, can be given subcutaneously, and does not increase PTT.
- Warfarin Mechanism: Inhibits synthesis of vitamin K-dependent coagulation factors (II, VI, IX, X, proteins C and S). Lab values: ↑ PT For rapid reversal give fresh frozen plasma, otherwise give vitamin K.Teratogen. ...
- tPA Mechanism: Aids conversion of plasminogen to plasmin, which breaks down fibrin. Lab values: ↑ PT, ↑ PTT Treat toxicity with aminocaproic acid.
- LMWH (enoxaparin) Mechanism: Mainly inhibits factor Xa. Lab values: Anti-factor Xa, although typically unmonitored. Protamine less effective at reversal than for heparin.
- Direct thrombin inhibitors (dabigatran, argatroban) ... Mechanism: Directly inhibits factor II (thrombin). No reversal agent.
- von Willebrand disease An autosomal dominant defect or deficiency in vWF with decreased levels of factor VIII, which is carried by vWF. Symptoms are due to platelet dysfunction and deficient factor VIII, and are milder than ...
- Hypercoagulable states - Factor V Leiden: A polymorphism in factor V, rendering it resistant to inactivation by activated protein C, is the most common cause of hereditary thromboembolic disease.- Heparin-induced thrombocytopenia ...
- Disseminated intravascular coagulation An acquired coagulopathy caused by deposition of fibrin in small blood vessels, leading to thrombosis and end-organ damage. Depletion of clotting factors and platelets leads to a bleeding diathesis. It ...
- Thrombotic thrombocytopenic purpura A deficiency of the vWF-cleaving enzyme (ADAMTS-13) resulting in abnormally large vWF multimers that aggregate platelets and create platelet microthrombi. These block off small blood vessels, leading ...
- Idiopathic thrombocytopenic purpura Diagnosis of exclusion in isolated thrombocytopenia (< 150,000/mm3) Etiology:- Primary ITP: inciting factor such as viral infection that causes an autoimmune reaction- Secondary ITP: associated with lymphoma, ...
- Hemolytic anemia (a normocytic anemia) Occurs when bone marrow production is unable to compensate for ↑ destruction of circulating blood cells. Etiologies include the following:- Glucose 6-phosphate dehydrogenase (G6PD) deficiency, paroxysmal ...
- G6PD deficiency X-linked defect in G6PD, leaving RBCs susceptible to hemolytic anemia following oxidant stress. Patients are often of Mediterranean or African descent, presenting with episodic dark urine and jaundice. ...
- Paroxysmal nocturnal hemoglobinuria An acquired genetic defect characterized by a triad of hemolytic anemia, pancytopenia, and thrombosis Pathophysiology:- Physiologically, a membrane-bound glycosylphosphatidylinositol (GPI) anchor protects ...
- Hereditary spherocytosis Autosomal dominant RBC membrane protein defectFrequently affected proteins:- Spectrin- Ankyrin- Band 3- Protein 4.2 Clinical features:- Anemia and pallor- Jaundice (due to ↑ unconjugated bilirubin)- ...
- Sickle cell anemia An autosomal recessive disorder caused by a mutation of adult hemoglobin (β-chain has Glu replaced by Val). Signs and symptoms are due to ↓ survival and a tendency of sickled cells to aggregate and ...
- Aplastic anemia Failure of blood cell production due to destruction of bone marrow cells.Acquired deficiency or absence of pluripotent stem cells. Etiology:- Idiopathic (in > 50%)- Fanconi anemia is a hereditary autosomal ...
- Thalassemias Hereditary disorders involving ↓ or absent production of normal globin chains of hemoglobin. Epidemiology:- Beta thalassemia: most commonly seen in people of Mediterranean descent- Alpha thalassemia: ...
- Polycythemia vera Chronic myeloproliferative neoplasm that is characterized by an erythropoietin-independent, irreversible increase in erythrocyte, granulocyte, and platelet counts.- Mutation in the JAK2 gene (95%) Clinical ...
- Blood transfusion reactions Febrile nonhemolytic reaction:- Mechanism: Cytokine formation during storage of blood.- Presentation: Fever, chills, rigors, and malaise 1-6 hours after transfusion.- Treatment: Stop the transfusion and ...
- Chronic lymphocytic leukemia (CLL) B-cell lymphoma that presents with lymphocytic leukocytosis. Epidemiology:- Median age at the time of diagnosis is 70-72 years- Most common type of leukemia in adults Rai staging system:0: Isolated ...
- Chronic myelogenous leukemia (CML) Clonal expansion of myeloid progenitor cells, leading to leukocytosis with excess granulocytes and basophils and sometimes ↑ erthrocytes and platelets as well. To truly be CML, the BCR-ABL translocation ...
- Hairy cell leukemia A malignant disorder of well-differentiated B lymphocytes. HCL accounts for 2% of adult leukemia cases and most commonly affects older men. History/PE:- Typically presents with pancytopenia, bone marrow ...
- Hodgkin lymphoma Epidemiology:- Bimodal age distribution: age 30 (primarily the nodular sclerosing type) and age 60 (maily the lymphocyte-depleted type) Etiology:- Strong association with Epstein-Barr virus (EBV)- Immunodeficiency: ...
- Multiple myeloma Clonal proliferation of malignant plasma cells with excessive production of monoclonal immunoglobulins (typically ineffective IgA or IgG) or immunoglobulin fragments (kappa/lambda light chains). MM primarily ...
- Waldenström macroglobulinemia A type of non-Hodgkin lymphoma associated with abnormal production of monoclonal IgM antibodies. Clinical features:- Impaired platelet function → hemorrhagic diathesis with petechial bleeding- Normochromic ...
- Amyloidosis Extracellular deposition of amyloid protein fibrils due to a variety of causes. Classically a disease of the elderly. History/PE:- Clinical presentation depends on the type, amount, and tissue distribution ...
- Iron deficiency anemia Etiology:- Decreased absorption: Bariatric surgery (duodenum), inflammatory bowel disease- Increased demand: Pregnancy, lactation, growth spurt- Iron loss: GI bleed, menorrhagia, hemorrhagic diathesis ...
- Sideroblastic anemia Etiology:- Inherited: X-linked sideroblastic anemia due to a δ-ALA-synthase gene defect- Acquired: Lead exposure, myelodysplastic syndromes, alcohol use disorder, vitamin B6, copper deficiency, isoniazid ...
- Folate deficiency Etiology:- Malnutrition: “Tea and toast” diet; alcohol use disorder- Malabsorption: e.g., celiac disease, inflammatory bowel disease- Increased requirement: e.g., pregnancy/lactation, severe hemolytic ...
- Myelodysplastic syndromes Group of hematological cancers in which malfunctioning pluripotent stem cells lead to hypercellularity and dysplasia of the bone marrow. Etiology:- Primary MDS (90% of cases): Tends to occur in elderly ...
- Red blood cell transfusion thresholds < 7 g/dL: Generally indicated 7-8 g/dL:- Cardiac surgery- Oncology patients in treatment- Heart failure 8-10 g/dL:- Symptomatic anemia- Ongoing bleeding- Acute coronary syndrome >10 g/dL: Not generally ...
- Acute intermittent porphyria Epidemiology:- Second most common porphyria- Peak incidence: ∼ 30 years- Sex: ♀ > ♂ (2:1) Etiology:- Autosomal dominant- Mutation of porphobilinogen deaminase - Attacks are triggered by:→ Anticonvulsants ...
- Porphyria cutanea tarda Epidemiology:- Most common porphyria- Peak incidence: 40-70 years- Sex: ♂ > ♀ Etiology: Defective uroporphyrinogen III decarboxylase (UROD)- Type I: acquired insufficiency of UROD in the context of ...
- Acute myeloid leukemia Epidemiology:- Most comon adult acute leukemia- Median age 65 Clinical features:- Fatigue is common (other B symptoms unusual)- Fatigue, weakness (anemia)- Bleeding, bruising (granulocytopenia)- Infection ...
- Sickle cell trait Clinical features:- Often asymptomatic- Painless gross hematuria due to renal papillary necrosis: often the only symptom- Hyposthenuria: nocturia, enuresis- Recurrent UTIs- Renal medullary carcinoma Laboratory ...
- Erythropoetin Stimulate red blood cell proliferation Indications:- CKD-related anemia Adverse effects:- Hypertension (30% of patients), which occurs 2-8 weeks after treatment initiation
- Heparin-induced thrombocytopenia (HIT) HIT can be differentiated into 1 (asymptomatic), and type 2, which is antibody-related and prognostically worse. Type 1 HIT:- Frequency: 10-20%- Onset: Within the first 5 days- Thombocytopenia: > 100,000/µl- ...
- Fanconi anemia A hereditary autosomal-recessive disorder due to a DNA crosslink repair defect.- Most common congenital cause of aplastic anemia (ie, bown marrow failure) Clinical features:- Short stature- Hypo-/hyperpigmented ...
- Medications that trigger hemolysis in G6PD deficiency ... Avoid:- Dapsone- Isobutyl nitrite- Nitrofurantoin- Primaquine- Rasburicase Use with caution:- Acetaminophen- Aspirin- Chloramphenicol- Chloroquine- Colchine- Diphenhydramine- Glyburide- Isoniazid- L-dopa- ...
- Indications for specialized RBC treatments Irradiated:- Bone marrow transplant (BMT) recipients- Acquired or congenital cellular immunodeficiency- Blood components donated by first or second degree relatives Leukoreduced:- Chronically transfused ...
- Tumor lysis syndrome Risk: Initiation of cytotoxic chemotherapy Manifestations:- Severe electrolyte abnormalities: ↑ Phosphorus, potassium, uric acid; ↓ Calcium- Acute kidney injury- Cardiac arrhythmias Treatment:- Continuous ...
- Polycythemia - Differential diagnosis Primary (↓ EPO):- Polycythemia vera (JAK2 mutation)- EPO receptor mutations Secondary (normal/↑ EPO):- Hypoxemia→ Cardiopulmonary disease→ Obstructive sleep apnea→ High altitude- EPO-producing ...
- Homocysteinuria Etiology:- Methionine synthase deficiency- Cystathione synthase deficiency- Impaired affinity of cystathione synthase for pyridoxal phosphate- Methylenetetrahydrofolate reductase deficiency Inheritance: ...
- Antiphospholipid antibody syndrome Diagnostic criteria: 1 clinical and 1 laboratory criterion must be met. Clinical:- Arterial/venous thrombosis- ≥ 3 consecutive unexplained fetal losses before 10th week- ≥ 1 explained fetal loss after ...
- Leukemoid reaction vs. CML Leukemoid reaction:- > 50'000/mm3- Cause: Severe infection, associated with certain solid tumors (e.g., lung and kidney cancer)- LAP score: High- Neutrophil precursors: More mature (metamyelocytes > myelocytes)- ...
- Echinocytes (burr cells) Smooth, rounded, and evenly spaced cytoplasmic projections Associated conditions:- Uremia- Liver disease
- Target cells (codocytes) Bullseye appearance Associated conditions:- Thalassemias- Hemoglobin C and S- Liver disease- Asplenia
- Acanthocytes (spur cells) Thorny projections with varying length and width (vs. echinocytes/burr cells) Associated conditions:- Hemolytic anemia in hepatic disorders (eg, liver cirrhosis)- Myelodysplastic syndromes- Asplenia- ...