USMLE (Fach) / Hematology and Oncology (Lektion)

In dieser Lektion befinden sich 111 Karteikarten

USMLE First Aid

Diese Lektion wurde von estoffel erstellt.

Lektion lernen

  • Thrombocytes - Involved in 1° hemostasis- Small cytoplasmic fragments derived from megakaryocytes- Life span of 8-10 days- When activated by endothelial injury, aggregate with other platelets and interact with fibrinogen ...
  • Neutrophils Acute inflammatory response cells. Numbers ↑ in bacterial infections. Phagocytic. Multilobed nucleus. - Specific granules contain leukocyte alkaline phosphatase (LAP), collagenase, lysozyme, and lactoferrin. - ...
  • Macrophages - Phagocytoses bacteria, cellular debris, and senescent RBCs.- Long life in tissues.- Name differs in each tissue type (eg, Kupffer cells in liver, histiocytes in connective tissue, Langerhans cells in ...
  • 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, ...
  • Basophils Mediate allergic reaction. - Densely basophilic granules contain heparin (anticoagulant) and histamine (vasodilator) (vs histaminase in eosinophils).- Leukotrienes synthesized and released on demand. ...
  • Mast cells Mediate allergic reaction in local tissues. Involved in type I hypersensitivity reactions. - Contain basophilic granules and originate from the same precursor as basophils but are not the same cell type. ...
  • B cells Part of humoral immune response. - Originate from stem cells in bone marrow and mature in marrow.- Migrates to peripheral lymphoid tissue (follicles of lymph nodes, white pulp of spleen, unencapsulated ...
  • T cell Mediate cellular immune response. - Originate from stem cells in the bone marrow, but mature in the thymus. - Differentiate into cytotoxic T cells (express CD8, recognize MHC I), helper T cells (express ...
  • ABO hemolytic disease of the newborn Type O mother with a type A, B, or AB fetus - Pre-existing maternal anti-A and/or anti-B igG antibodies cross placenta → HDN in the fetus - Mild jaundice in the neonate within 24 hours of birth. - ...
  • Acanthocyte ("spur cell") Liver disease, abetalipoproteinemia (states of cholesterol dysregulation)
  • Basophilic stippling Lead poisoning, sideroblastic anemias, myelodysplastic syndromes, thalassemias. Seen primarily in peripheral smear vs ringed sideroblasts seen in bone marrow. Aggregation of residual ribosomes.
  • Dacrocyte ("teardrop cell") Bone marrow infiltration (eg, myelofibrosis), thalassemias. RBC "sheds a tear" because it's mechanically squeezed out of its home in the bone marrow
  • Degmacyte ("bite cell") G6PD deficiency
  • Echinocyte ("burr cell") End-stage renal disease, liver disease, pyruvate kinase deficiency Different from acanthocyte; its projections are more uniform and smaller.
  • Elliptocyte Hereditary elliptocytosis, usually asymptomatic; caused by mutation in genes encoding RBC membrane proteins (eg, spectrin)
  • Macro-ovalocyte Megaloblastic anemia (also hypersegmented PMNs), marrow failure
  • Ringed sideroblast Sideroblastic anemia. Excess iron in mitochondria. Seen in bone marrow with special staining (Prussian blue), vs basophilic stippling in peripheral smear.
  • Schistocyte Microangiopathic hemolytic anemias, including DIC, TTP/HUS, HELLP syndrome, mechanical hemolysis (eg, heart valve prothesis). Fragmented RBCs (eg, helmet cells)
  • Sickle cell Sickle cell anemia. Sickling occurs with dehydration, deoxygenation, and at high altitude.
  • Spherocyte Hereditary spherocytosis, drug- and infection-induced hemolytic anemia. Small, spherical cells without central pallor.
  • Target cell HbC disease, asplenia, liver disease, thalassemia
  • Heinz bodies Seen in G6PD deficiency. Oxidation of Hb -SH groups to -S--S- → Hb precipitation (Heinz bodies), with subsequent phagocytic damage to RBC membrane → bite cells.
  • Howell-Jolly bodies Seen in patients with functional hyposplenia or asplenia. Basophilic nuclear remnants found in RBCs. Howell-Jolly bodies are normally removed from RBCs by splenic macrophages.
  • α-Thalassemia α-globin gene deletions → ↓ α-globin synthesiscis deletion (--/αα) prevalent in Asian populationstrans deletion (-α/-α) prevalent in African populations (offspring don't develop HbH or hydrops ...
  • β-Thalassemia Point mutations in splice sites and promotor (eg, Kozak) sequences → ↓ β-globin synthesis. In contrast to α-globin chain genes, the 2 β-globin chain genes are expressed postnatally only, and therefore ...
  • Lead poisoning Lead inhibits ferrochelatase and ALA dehydratase → ↓ heme synthesis and ↑ RBC protoporphyrin, ALA. - Also inhibits rRNA degradation → rRNA aggregates (basophilic stippling). Symptoms:- Lead lines ...
  • Sideroblastic anemia Disorder in which the body has adequate iron stores, but is unable to incorporate the iron into hemoglobin. Causes: - Genetic (eg, X-linked defect in ALA synthase gene)- Acquired (myelodysplastic syndromes)- ...
  • Folate deficiency Causes: - Malnutrition (eg, alcoholics)- Malabsorption- Drugs (eg, methotrexate, trimethoprim, phenytoin)- ↑ requirement (eg, pregnancy, hemolytic anemia) Findings:- ↑ homocysteine, normal methylmalonic ...
  • Vitamin B12 (cobalamin) deficiency Causes:- Insufficient intake (eg, veganism)- Malabsorption (eg, Crohn disease)- Pernicious anemia- Diphyllobothrium latum (fish tapeworm)- Gastrectomy Findings:- ↑ homocysteine, ↑ methylmalonic ...
  • Orotic aciduria Inability to convert orotic acid to UMP (de novo pyrimidine synthesis pathway) because of defect in UMP synthase.- Autosomal recessive. Presents in children as failure to thrive, developmental delay, ...
  • Intravascular vs extravascular hemolysis Intravascular hemolysis:- ↓ haptoglobin, ↑ LDH, ↑ schistocytes, ↑ reticulocytes on blood smear.- Characteristic hemoglobulinuria, hemosiderinuria, and urobilinogen in urine.- May also see ↑ ...
  • Anemia of chronic disease Inflammation → ↑ hepcidin (released by liver, binds ferroportin on intestinal mucosal cells and macrophages, thus inhibiting iron transport) → ↓ release of iron from macrophages and ↓ iron ...
  • Aplastic anemia Bone marrow failure due to hematopoietic stem cell deficiency (CD34+). Causes:- Autoimmune- Radiation and drugs (eg, benzene, chloramphenicol, alkylating agents, antimetabolites)- Viral agents (parvovirus ...
  • Hereditary spherocytosis Extravascular hemolysis due to defect in proteins interacting with RBC membrane (eg, ankyrin, band 3, protein 4.2, spectrin).- Mostly autosomal dominant inheritance. Results in small, round RBCs with ...
  • G6PD deficiency Most common enzymatic disorder of RBCs. Causes extravascular and intravascular hemolysis.- X-linked recessive- African, Mediterranean, and Asian descent Defect in G6PD → ↓ glutathion → RBC susceptibility ...
  • Pyruvate kinase deficiency Defect in pyruvate kinase → ↓ ATP → rigid RBCs → extravascular hemolysis.- Autosomal recessive- In glycolysis, pyruvate kinase converts phosphoenolpyruvate into pyruvate irreversibly. This ...
  • Paroxysmal nocturnal hemoglobinuria Acquired mutation of PIGA gene that encodes a GPI anchor for decay-accelerating factor (DAF/CD55) and membrane inhibitor of reactive lysis (MIRL/CD59) in the cell membrane → ↑ complement-mediated ...
  • Sickle cell anemia HbS point mutation causes a single amino acid replacement in β chain (substitution of glutamic acid with valine). Causes extravascular and intravascular hemolysis.- 8% of African Americans carry and ...
  • Autoimmune hemolytic anemia Warm (IgG) – chronic anemia seen in SLE and CLL and with certain drugs (eg, α-methyldopa). Cold (IgM and complement) – acute anemia triggered by cold; seen in CLL, Mycoplasma pneumonia infections, ...
  • Microangiopathic anemia RBCs are damaged when passing through obstructed or narrowed vessel lumina. Seen in DIC, TTP/HUS, SLE, HELLP, and hypertensive emergency. - Schistocytes (eg, "helmet cells") are seen on peripheral blood ...
  • Macroangiopathic anemia Prosthetic heart valves and aortic stenosis may also cause hemolytic anemia 2° to mechanical destruction of RBCs. Findings: Schistocytes on peripheral blood smear
  • Neutropenia Absolute neutrophil count <1500 cells/mm3Severe 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 (severe combined immune deficiency)- SLE- corticosteroids- radiation- sepsis, postoperative
  • Eosinopenia Absolute eosinophil count <30 cells/mm3 Causes:- Cushing syndrome- corticosteroids
  • Left shift ↑ neutrophil precursors, such as band cells and metamyelocytes, in peripheral blood. Usually seen with neutrophila in the acute response to infection or inflammation. Called leukoerythroblastic reaction ...
  • Acute intermittent porphyria Deficient enzyme: Porphobilinogen deaminaseAccumulated substrate: Porphibilinogen, δ-ALA- Autosomal dominant  Symptoms:- Painful abdomen- Port wine-colored urine- Polyneuropathy- Psychological distrubances- ...
  • Porphyria cutanea tarda Deficient enzyme: Uroporphyrinogen decarboxylaseAccumulated substrate: Uroporphyrin (tea-colored urine)- Autosomal dominant Symptoms:- Blistering cutaneous photosensitivity and hyperpigmentation - Most ...
  • Coagulation tests PT – tests function of common and extrinsic pathway (factors VII, X, V, II, I). INR (international normalized ratio) – calculated from PT. 1 = normal, >1 = prolonged. Most common test used to follow ...
  • Hemophilia A, B, or C Intrinsic pathway coagulation defect (↑ PTT).A: deficiency of factor VIII → X-linked recessiveB: deficiency of factor IX → X-linked recessiveC: deficiency of factor XI →  autosomal recessive- ...
  • Vitamin K deficiency General coagulation defect. Bleeding time normal. ↓ activity of factors II, VII, IX, X, protein C, protein S ↑ PT↑ PTT