the hematopoietic and lymphoid systems

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the hematopoietic and lymphoid systems
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hematopathology

• blood
• lymphoid organs
• central
• bone marrow
• thymus
• peripheral
• lymph nodes
• MALT (Waldeyers ring, intestine...)
• splenic white pulp

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hematopathology

• leukaemia neoplastic cells in peripheral blood
• lymphoma tumour of the lymph node
• hemoblastosis
• primary bone marrow
• leukaemia tumoriform
• lymphomas
• primary lymph nodes
• lymphoma leukemic phase

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bone marrow
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bone marrow

• weight cca 1,5kg
• red (hematopoietic) x yellow (adipose)
• structure
• hematopoietic cells granulopoiesis
  peritrabecular, erytropoiesis a megakaryocytes
  intertrabecular and perisinusoidal
• corroborative elements makrophages, fibroblasts,
  mastocytes, plazmocytes, lymfocytes
• blood sinuses
• bone trabeculas

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diminished hematopoiesis

• A) total diminution
• aplastic anemie (panmyelophtisis)
• hereditary
• Fanconi anemia
• AR
• death because of infectious and bleeding
  complications
• /- turn into AML
• acquired
• infectious, irradiation, use of some drugs

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diminished hematopoiesis

• B) selective
• one or more of hematopoietic lineages critical is
  peripheral blood marrow could be hypercelular
  ineffective hematopoiesis

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diminished hematopoiesis...anemia

• 1) anemia
• ? total circulating RBC volume, /- ?Hb and ?O2
• hypoxia of tissues clinical symptoms

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anemia...loss of RBC

• a) hemorrhage blood loss anemia
• hypovolemia ? normocytic normochromic anemia ? ?
  erytropoiesis (bone marrow) ? reticulocytosis,
  hypochromic anemia

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anemia...hemolytic

• b) increased rate of RBC destruction the
  hemolytic anemias
• anemia reactive hyperplastic erytropoiesis
• bm ?erytropoiesis/myelopoiesis, gaucheroid cells
• /- extramedullary hematopoiesis
• Hb -emia, -uria

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anemias..hemolytic..intrinsic

• I) intrinsic (intracorpuscular) abnormalities of
  RBC
• hereditary
• 1) disorders of RBC membrane cytoskeleton
• spherocytosis
• erythrocytes spheroidal, less deformable and
  vulnerable to splenic sequestration and
  destruction
• AD
• anemia, splenomegalia a hemolytic icterus

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anemias..hemolytic..intrinsic

• 2) RBC enzyme deficiencies
• 3) disorders of Hb synthesis hemglobin
• deficient globin synthesis thalassemia syndromes
• lack of or decreased synthesis of globin
  chains a chains a thalassemia
  ß chains ß
  thalassemia
• ? synthesis of Hb ? anemia (microcytic
  hypochromic) excess of a chains in ß
  thalassemia ? insoluble aggregats ? damage RBC
  membrane ? reduction of plasticity ?
  phagocytosis, inefective erytropoiesis
• heterozygous thalassemia minor
  homozygous thalassemia major

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anemias..hemolytic..intrinsic

• structurally abnormal globin synthesis
  (hemoglobinopathies) sickle cell anemia
• atructurally abnormal Hb S on deoxygenation
  polymerization gelation or crystallization ?
  microvascular obstruction ? ischemic tissue
  damage ? removing in the spleen
  autosplenectomy

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anemias..hemolytic..intrinsic

• acquired
• membrane defect paroxysmal nocturnal
  hemoglobinuria)
• ?resistance against C3
• granulocytes and plateles affected too ?
  hemolysis, /- trombotic complications and ?
  susceptibility to infections

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anemias..hemolytic..extrinsic

• II) extrinsic (extracorpuscular) abnormalities
• 1) antibody mediated
• isohemagglutinins
• erythroblastosis fetalis
• Rh (mother Rh-, father and child Rh)
• antibodies against fetal RBC
• hydrops fetus universalis, mental retardation,
  ?extramedulary hematopoiesis

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anemias..hemolytic..extrinsic

• autoantibodies
• idiopathic (primary), drug associated, SLE
• Coombs tests

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anemias..hemolytic..extrinsic

• 2) mechanical trauma to RBCs
• mikroangiopathic hemolytic anemias
• DIC, TTP
• mechanic traumatization of erythrocytes
• dialysis, valves prosthesis
• 3) infections (malaria)

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anemia...impaired RBC production

• c) diminished erythropoiesis
• 1) combination with the others in aplastic
  anemia
• 2) pure erytroblastophtisis
• Blackfan-Diamond syndrom
• children
• thymomas and T-CLL
• 3) myelophtisic anemia
• extensive replacement of the marrow by tumours or
  other lesions ? extramedulary hematopoiesis,
  leukoerythroblastosis

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anemia...impaired RBC production

• 4) iron deficiency anemia
• most common
• mikrocytar hypochromic
• ?low intake (diets, malabsorptions) x ? demands
  (pregnancy, infancy, chronic blood loss)
• gross hypoxic myocardial steatosis
• marrow normal or hyperplastic erythropoiesis,
  decline in serrum ferritin and depletion of
  stainable iron in the bone marrow

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anemia...impaired RBC production

• 5) megaloblastic anemia
• disturbance of proliferation and differentiation
  of erythroblasts ? megaloblasts, megakaryocytes
• nuclear-cytoplasmic asynchrony
• giant metamyelocytes ? hypersegmented neutrophils
• ineffektive erythropoiesis
• folate (folic acid) deficiency anemia
• tetrahydrofolate
• neurologic abnormalities do not occur

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anemia...impaired RBC production

• pernicious anemia
• vitamin B12 (cobalamin) deficiency
• diet, ?intrinsic faktor (parietal gastric cells),
  terminal ileum
• gross atrophic glossitis, gastritis,
  demyelinization

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anemia...impaired RBC production

• 6) lack of erythropoietin
• kidney failure, parvovirosis (B19)

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diminished hematopoiesis... leukopenia

• 2) leukopenia
• a) lymfopenia
• hereditary immunity disorders, infections(viral),
  chronical diseases, steroid therapy

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leukopénie

• b) neutropenia (granulocytopenia)
• increased susceptibility to infections
• marrow failure (aplastic anemia) ?
  agranulocytosis
• inadequate or ineffective granulopoiesis certain
  drugs benzen, purin and pyrimidin analogs,
  anthracyklin x idiosyncrastic reaction
  (chloramfenikol, chlorpromazin, fenylbutazon)
• accelerated removal or destruction of
  neutrophils hypersplenism, certain drugs
• bm depend on the underlying basis ? or ?
  granulopoiesis and /- reaction to infection

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increased hematopoiesis

• transitory increasing of hematopoiesis
• 1) ?erythropoiesis polycythemia
• increased erythropoietin levels
• appropriate lung disease, high-altitude living,
  cyanotic heart disease
• inappropriate erythropoietin-secreting tumours,
  doping
• bm hypercellular, inappropriate increasing of
  erythropoiesis
• no extramedullary hematopoiesis!

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increased hematopoiesis

• 2) leukocytosis
• a) lymfocytosis chronical infections (IM)
• b) granulocytosis acute bacterial infections
  (pyogenic organisms), sterile inflammation
  (tissue necrosis, burns) ? leukemoid reaction
  (like in CML)
• c) eosinophilia allrgic disorders, parasitic
  infestation, drug reaction, certain mlg
• 3) thrombocytosis infections, chronical
  bleeding, tumours, iron deficiency

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myelodysplastic syndromes

• heterogeneous group of disorders
• some evidence of bone marrow failure and
  dysplasia in one or more myeloid cell lineages
• may evolve to AML
• chromosomal aberrations
• primary x secundary (radiotherapy, alkylating
  agent therapy)
• bm hypercellular, ? erythropoiesis, morphological
  changes, /- fibrosis

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myelodysplastic syndromes...histological
classification

• refractory anemia (RA)
• refractory anemia with ring sideroblasts (RARS)
• refractory cytopenia with multilineage dysplasia
• refractory anemia with excess blasts (RAEB)
• MDS, unclassifiable

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chronic myeloproliferative diseases

• CMPDs clonal haematopoietic stem cell disorders
  characterised by proliferation in the bone marrow
  of one or more of the myeloid (i.e. granulocytic,
  erythroid and megakaryocytic) lineages

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CMPD

• A) chronic myelogenous leukaemia
• most common
• adults, 30-60eyars
• neutrophilic leukocytosis in peripheral blood
• Ph t(922) Philadelphia chr.
• bm hypercellular (?granulopoiesis,
  ?megakaryocytes), /- fibrosis
• extramedullary leukaemic infiltration spleen,
  liver
• ? accelerated phase ? blast phase

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CMPD

• B) polycythaemia vera (polycythaemia rubra vera,
  m. Vaquez-Osler)
• ? erythropoiesis
• hypertension, thrombosis, haemorrhage
• bm
• initial phase hypercellular, with increased
  erythropoiesis extramedullar infiltration ?
  hepatosplenomegaly
• /- blast phase or spent phase

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CMPD

• C) essential thrombocythaemia
• proliferation primarly magakaryocytic lineage
• sustained thrombopcytosis in the blood
• bm large, mature megakaryocytes
• D) chronic idiopathic myelofibrosis
• proliferation of mainly megakaryocytes,
  associated with reactive deposition of bone
  marrow connective tissue and extramedullary
  hematopoiesis

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acute leukaemias

• causes
• complication of certain chromosomal disease (m.
  Down, Fanconiho anémie, Klinefelteruv syndrom...)
• radiation
• chemicals (benzen, alkylating agents, drugs)
• viruses (HTLV-1)
• AML, ALL
• symptoms combination of aplastic anemia and
  agranulocytosis
• bm leukaemic infiltration, /- extramedullar
  infiltration (liver, spleen, kidney, CNS)
• myelosarcoma (chloroma)

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acute myeloid leukaemias... histological
classification

• M0...acute myeloblastic l. minimally
  differentiated
• M1 ...acute myeloblastic l. without maturation
• M2...acute myeloblastic l. with maturation
• M3...acute promyelocytic l.
• M4...acute myelomonocytic l.
• M5...akutní monocytic l.
• M6...acute erythroid l.
• M7...acute megakaryoblastic l.

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acute lymphoblastic leukaemias... histological
classification

• precursor B- and T- cell lymphoblastic
  leukaemia/lymphoblastic lymphoma

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proliferation of macrophages, histiocytosis

• A) reactive proliferation of macrophages
• bone marrow, many causes (hemosiderosis, aiha,
  viral infections)
• lysosomal storage diseases (m. Gaucher,
  Niemann-Pick...)

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proliferation of macrophages, histiocytosis

• B) hemofagocytic syndroma
• ? proliferation of macrophages or histiocytic
  precursores ? haemofagocytosis ? cytopenia
• hepatosplenomegaly, fever
• proliferating macrophages clonal (mlg
  histiocytosis) x reaction (infection, Kawasaki, T
  lymphomas)
• fatal haemofagocytosis

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proliferation of macrophages, histiocytosis

• C) histiocytosis X (Langerhans cells
  histiocytosis)
• 1) solitary eosinophilic granuloma
• bng
• bones (unifocal lytic lesion), skin, lymph nodes,
  lungs
• Langerhans cells (birbeck granules)
  eosinophils, /- plasma cells and lymphocytes
• 2) m. Hand-Schüler-Christian
• trias multifocal lytic lesions of bone
  exophtalamus diabetes insipidus

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proliferation of macrophages, histiocytosis

• 3) m. Abt-Letterer-Siwe
• mlg
• children before 2 years of age
• cutaneous lesions resembling seborrheic skin
  eruptions hepatosplenomegaly, lymphadenopathy,
  pulmonary lesions, osteolytic bone lesions ?
  anemia and thrombocytopenia, reccurent infections
  

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metastasis

• osteolytic x osteoplastic
• prostate, breast, stomach, lung cancer

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bone marrow necrosis

• ischemia
• vascular collaps in hypercellular marrow
• metastatic obstruction
• sickle cell disease, DIC...
• symptoms pain, fever, hematopoietic precursors
  in peripheral blood

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transplantation

• transplantation bone marrow, peripheral stem
  cells
• autologous x allogenneous (relatives,
  non-relatives)
• indications
• hematological tumours, immunodeficiency,
  anemias, b.m. aplasia
• non-hematological tumour metastasis

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transplantation

• bone marrow suppression ? graft
• hypocellularity ? proliferation
• immunosuppression!
• GvHD acute x chronic
• skin, intestine, liver

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bleeding disorders

• cause
• defect in the vessel wall
• platelet deficiency or dysfunction
• derangement of coagulation factors

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bleeding disorders...vascular

• A) defects in the vessel wall
• 1) hereditary
• a) m. Osler-Rendu-Weber (hereditary hemorhagic
  teleangiektasias)
• capillary aneurysms in the skin and mucous
  membranes
• b) connective tissue disorders
• m. Ehlers-Danlos
• Marfans syndrome

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bleeding disorders...vascular

• 2) acquired
• a) avitaminosis C, ? kortikosteroids
• cutaneous, intramuscular, mucosal bleeding
• b) purpura Henoch-Schönlein
• circulating IC ? skin, kidney

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bleeding disorders...plateles

• B) plateles deficiency or dysfunction
• 1) thrombocytopenia
• a) decresed production
• aplastic anemia
• hereditary disorders (sy Bernard-Soulier,
  grey-plateles sy, m. Wiskott-Aldrich)

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bleeding disorders...plateles

• b) increased destruction
• splenomegaly, arteficial valves,...
• DIC (disseminated intravascular coagulation)
• activation of the coagulation sequence, leading
  to formation of thrombi throughout the
  microcirculation ? consumption of plateles and
  coagulation factors and secondarily activation of
  fibrinolysis

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bleeding disorders...plateles

• thrombotic thrombocytopenic purpura (TTP)
• thrombocytopenia, fever, microvessel obstruction
  symptoms
• ? microangiopathic hemolytic anemia
• hyaline thrombi in the microcirculation
• hemolytic-uremic syndrome (HUS)
• E.coli
• kidney cortex necrosis, intestinal bleeding

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bleeding disorders...plateles

• idiopathic thrombocytopenic purpura (ITP)
• autoimmune origin
• destruction in the spleen ? splenectomy
• bm /- increased megakaryopoiesis

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bleeding disorders...plateles

• 2) platelet dysfunction
• adhesion disorder (Bernard-Soulier, m. von
  Willebrand)
• aggregation disorder (thrombasthenia Glanzmann)
• secretion disorder tromboxan A2 inhibition
  (aspirin)

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bleeding disorders...coagulation factors

• C) coagulation disorders
• 1) hereditary deficiencies
• a) hemophilia A (classic hemophilia)
• f VIII (severe activity lt 1!)
• X chromosoma (new mutation x familiar)
• easy bruising and massive hemorrhage after trauma
  or operative procedures, spontaneous
  hemorrhages joints (hemarthroses) ? progressive
  deformities
• b) hemophilia B (Christmas disease)
• f IX

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bleeding disorders...coagulation factors

• 2) acquired
• a) DIC
• b) liver diseases
• synthesis of coagulation factors (fibrinogen,
  prothrombin, fV, VII, IX-XI) anticoagulation
  and fibrinolytic factors
• c) vitamin K
• food, synthesis in the large intestine
  (bacterias)
• d) anticoagulation therapy

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lymph vessels and nodes
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lymphatic vessels

• A) lymphoedema
• lymph is protein-rich ? lymphostasis leads to
  fibroproduction, /- infectious and ulcerative
  complications
• 1) hereditary Milroys disease
• valvular disorder
• 2) acquired lymphoedema
• lymphoedema praecox
• secondary lymphoedema obstruction and
  lymphostasis (mlg, inflammatory changes)

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lymphatic vessels

• B) lymphangiectasia
• focal extension of lymphatic vessels
• skin, small intestine (chylangiectasia)
• ? lymforhea (chylothorax...)

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lymphatic vessels

• C) lymphangiitis
• lymph vessels draining the primary (infectious)
  focus
• ß hemolytic streptococci
• regional lymphadenitis
• clinical red subcutaneous line
• histology
• lymphangiitis simplex
• lymphangiitis purulenta pus fibrin ? spreading
  ? abscesses, trombophlebitis

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lymfatic nodes...structure

• cells lymphocytes, dendritic cells (FDRC, IDRC),
  macrophages with apoptotic bodies, NK cells
• follicles B zone
• lymphocytes from the bm ? primary follicle ?
  immunity stimulation ? germinal centres
  secondary follicle, immunity answer ?
  polarization of germinal centres
• germinal centres B cells augmentation, selection
  Ag high affinity clones ? plasma cells
  differentiation ? migration into medulla, waiting
  to secondary immunity answer

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lymph nodes...structure

• medulla
• lymphatic tissue between medullar sinuses
• small lymphocytes, plasma cells
• paracortex T zone
• mainly CD4 T cells, small venules
• T lymphocytes 70 of lymphocytes in lymph node
  and 80-90 in blood
• sinuses
• incoming lymph vessels ? subcapsular (marginal)
  sinus ? interfollicular ? medulla ? outgoing
  vessels

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lymph nodes...regressive changes

• A) regressive changes and circulatory disorders
• 1) infarction
• vasculitis
• tumorous infiltration
• vascular transformation of sinuses
• 2) atrophy
• lipomatous
• hyalin
• 3) pigmentation
• 4) amyloidosis
• 5) storage diseases

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lymph nodes...inflammation

• B) lymphadenitis
• 1) acute nonspecific
• inflammation of regional lymph node
• clinicaly enlarged, erythematous lymph nodes
• histology ? follicles, mitoses, sinuses filled
  with granulocytes, histiocytes
• /- healing with fibrous scarse

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lymph nodes...inflammation

• 2) chronic nonspecific lymphadenitis
• etiology
• a) follicular hyperplasia
• etio tonsillitis, respiratory infections, RA,
  syphilis, AIDS
• histology ? germinal centers, fanciful shapes,
  many mitoses, blastic forms of cells could be
  misinterpreted like mlg lymphoma!

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lymph nodes...inflammation

• progressive transformation of germinal centres
• connection with HD (paragranuloma)
• m. Castleman (angiofollicular hyperplasia)
• lolly pops follicles
• unifocal bng x multifocal fatal

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lymph nodes...inflammation

• b) paracortical hyperplasia
• etio viruses (IM, HSV), inoculation, some drugs
• histology enlarged paracortex, with many IDRC,
  small follicles in the periphery of the lymph
  node, T imunoblasts
• c) reactive sinusoidal histiocytosis
• etio reactive (different Ag)
• histology dilated sinuses filled with histiocytes

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lymph nodes...inflammation

• m. Rosai-Dorfman (masive sinusoidal
  histiocytoses)
• intrasinusoidal macrophages with emperipolesis
• d) mixed reactive hyperplasia
• etio toxoplasmosis (epitheloid granulomas)

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lymph nodes...inflammation

• 3) granulomatus purulent
• epitheloid granulomas with central necrosis with
  accumulation of neutrophils
• cat scratch disease
• veneric lymphogranuloma (Chl.trachomatis)
• mesenterial lymphadenitis (Y.enterocolitica)
• ulcus molle (H. ducreyi)

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lymph nodes...inflammation

• 4) granulomatous necrotic
• tularemia (Fr. tularensis)
• plague (Y. pestis)
• anthrax (B. antracis)
• 5) granulomatous
• tuberculoid granulomas without central necrosis
• sarcoidosis, m. Crohn...
• 6) TBC lymphadenitis
• miliary x caseous productive

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lymph nodes...inflammation

• 7) granulomatous reaction to lipid materials
• m. Whipple
• lipid vacuoles, around epitheloid histiocytes,
  intracytoplasmic PAS material
• 8) granulomatous reaction to foreign bodies
• silicic material in prosthesis

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lymph nodes...neoplasms

• C) neoplasms, malignant lymphomas
• 1) m. Hodgkin (HD)
• group of disesases
• presence of distinctive neoplastic giant cells
  Reed-Sternberg cells, Hodgkin cells, admixed with
  a variable infiltrate of reactive, nonmalignant
  inflammatory cells
• young people

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lymph nodes...neoplasms...HD

• classification
• nodular lymphocytic predominance Hodgkin lymphoma
• classic
• lymphocyte rich HL (LR-CHL)
• nodular sclerosis (NS-CHL)
• mixed cellularity (MC-CHL)
• lymfocyte depleted (LD-CHL)

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lymp nodes...neoplasms...NHL

• 2) non Hodgkin lymphomas
• predominance of neoplastic cells
• elder patients
• B and T cells

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lymph nodes...neoplasms...B-NHL

• a) B-NHL
• chronic lymphocytic leukaemia/small lymphocytic
  lymphoma (CLL/SLL)
• follicular lymphoma (FCL)
• mantle cell lymphoma (MCL)
• marginal zone lymphoma (MZL) SMZL, ENMZLMALT,
  NMZL
• hairy cell leukaemia (HCL)
• diffuse large B-cell lymphoma (DLBCL)
• Burkitt lymphoma

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lymph nodes...neoplasms...B-NHL

• plasma cell neoplasms
• monoclonal gammopathy of undetermined
  significance (MGUS)
• lymphoplasmacytic lymphoma (LPL), m. Waldenström
• plasmacytoma
• multiple myeloma

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lymph nodes...neoplasms...T-NHL

• b) T-NHL
• peripheral T cell lymphoma (PTL)
• anaplastic large T cell lymphoma (ALCL)
• angioimmunoblastic T cell lymphoma (AILT)
• adult T cell leukaemia
• mycosis fungoides/Sezary syndrom

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spleen
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spleen

• structure
• white pulp lymphoid tissue
• red pulp venous sinuses ? hilus
• splenomegaly venosthasis, inflammation,
  neoplasms
• hypersplenism increased function ? cytopenia
• hyposplenism ? susceptibility to certain
  bacterial infections

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spleen...regressive changes, circulatory disorders

• A) inborn anomalies
• accessory spleens spleniculi
• B) regressive changes and circulatory disorders
• 1) amyloidosis
• secondary (AA)
• /- hyposplenism

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spleen...regressive changes, circulatory disorders

• 2) storage diseases
• 3) hemolytic anemias
• ? splenic function ? splenomegaly
• hereditary spherocytosis
• 4) chronic perisplenitis
• 5) infarkt sleziny
• white (embolization, vasculitis)
• red (thrombosis of lienal vein)

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spleen...regressive changes, circulatory disorders

• 6) chronic venosthasis
• 7) splenic rupture, bleeding
• traumatic

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spleen...inflammation

• A) inflammation
• 1) acute septic tumour
• reaction to general infection x tumour lysis
• clinicaly tense capsula, soft tissue
• histology red pulp cellular, small abscesses
  (central pyemia)

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spleen...inflammation

• 2) chronic inflammatory tumour
• chronic infections (IE)
• histology red pulp hyperemia, reactive
  hyperplasia of the white pulp
• malaria
• TBC, histoplasmosis, leishmaniosis,
  trypanosomiasis
• AIDS

82
spleen...tumours

• D) tumours and pseudotumours
• 1) cystic formations
• posttraumatic pseudocysts
• parasitary cysts
• /- dermoid cyst
• 2) hamartoma (splenoma)
• nodule
• histology chaotic sinuses a fibrus tissue
  incorrect arrangement of the red pulp
• /- hypersplenism

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spleen...tumours

• 3) hemangioma
• histology cavernous blood spaces, thrombosis
• 4) littoral cell angioma
• phagocytosis ? pancytopenia
• 5) inflammatory pseudotumour
• histology inflammatory cells fibroproduction

84
spleen...tumours

• 6) malignant lymphomas
• primary SMZL
• secondary
• more often
• secondary infiltration by NHL, HD, CML, HCL
• 7) epithelial metastasis
• microscopically

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thymus
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thymus...structure

• structure
• lobulus
• cortex and medulla mixture of T lymphocytes and a
  epithelial cells lymphoepithelial organ
• cortex mainly T lymphocytes
• lymphatic follicles without germinal centres
• medulla thymocytes, Hassal bodies

87
thymus...function

• function
• production of small lymphocytes with cellular
  immunity
• TdT a CD1 ? maturation ? CD4 a CD8 ? postthymic
  lymfocytes in medulla CD4 (helpers/inducers),
  CD8 (suppressor/cytotoxic), loss of TdT a CD1 ?
  blood, peripheral lymphatic organs
• main role intrauterine and in childhood

88
thymus...dysgenesis

• A) thymic dysgenesis
• primary immunodeficiency syndromes (diGeorge,
  Nezelof...)

89
thymus...regressive changes

• B) regressive changes
• 1) lipomatous atrophy (involution)
• puberty involution with increase of adipous
  tissue ? thymocytes, calcification of Hassal
  bodies...
• 2) acute (accidental) involution
• etio corticosteroids stress
• histology fragmentation of cortical thymocytes,
  cystic transformation of Hassal. bodies,
  lymfocytes disappeared, in cortex only spindle
  epithelial cells

90
thymus...hyperplasia

• C) thymic hyperplasia
• primary hyperplasia
• myasthenia gravis
• histology lymphoid hyperplasia, lymphatic
  follicles with germinal centres
• Ab anti acetylcholin-receptors

91
thymus...neoplasms

• D) neoplasms
• 1) thymomas
• epithelial thymic cells lymphocytes
• local manifestation
• association with myasthenia gravis
• 2) neuroendocrinne tumors
• 3) germinal cells tumours (teratoma, seminoma)
• bng, cystic
• 4) malignant lymphoma