Hematopathology

1. the hematopoietic and
lymphoid systems

2. hematopathology
• blood
• lymphoid organs
– central:
•bone marrow
•thymus
– peripheral:
•lymph nodes
•MALT (Waldeyer´s ring,
intestine...)
•splenic white pulp

3. 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

4. bone marrow

5. 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

6. diminished hematopoiesis
A) total diminution
aplastic anemia (panmyelophtisis)
• hereditary:
– Fanconi anemia
• AR
• death because of infectious and bleeding
complications
• +/- turn into AML
• acquired:
– infectious, irradiation, use of some drugs

7. diminished hematopoiesis
B) selective
• one or more of hematopoietic lineages
critical is peripheral blood – marrow could
be hypercelular = „ineffective
hematopoiesis“

8. diminished
hematopoiesis...anemia
1) anemia
• ↓ total circulating RBC volume, +/- ↓Hb
and ↓O2
• hypoxia of tissues = clinical symptoms

9. anemia...loss of RBC
a) hemorrhage: blood loss anemia
• hypovolemia → normocytic
normochromic anemia → ↑ erytropoiesis
(bone marrow) → reticulocytosis,
hypochromic anemia

10. 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

11. 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

12. anemias..hemolytic..intrinsic
2) RBC enzyme deficiencies
3) disorders of Hb synthesis: hem+globin
deficient globin synthesis: thalassemia
syndromes
– lack of or decreased synthesis of globin chains:
α chains = α thalassemia
β chains = β thalassemia
– ↓ synthesis of Hb → anemia (microcytic hypochromic)
+ excess of α chains in β thalassemia → insoluble
aggregats → damage RBC membrane → reduction of
plasticity → phagocytosis, inefective erytropoiesis
– heterozygous = thalassemia minor
homozygous = thalassemia major

13. anemias..hemolytic..intrinsic
structurally abnormal globin synthesis
(hemoglobinopathies): sickle cell anemia
– structurally abnormal Hb S – on
deoxygenation polymerization = gelation or
crystallization → microvascular obstruction
→ ischemic tissue damage + ↑ removing in
the spleen = „autosplenectomy“

14. anemias..hemolytic..intrinsic
 acquired
membrane defect: paroxysmal nocturnal
hemoglobinuria)
– ↓resistance against C3
– granulocytes and plateles affected too →
hemolysis, +/- trombotic complications and
↑ susceptibility to infections

15. 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

16. anemias..hemolytic..extrinsic
 autoantibodies
– idiopathic (primary), drug associated, SLE
– Coombs tests

17. anemias..hemolytic..extrinsic
2) mechanical trauma to RBCs
 mikroangiopathic hemolytic anemias
– DIC, TTP
 mechanic traumatization of
erythrocytes
– dialysis, valves prosthesis
3) infections (malaria)

18. 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 → extramedullary
hematopoiesis, leukoerythroblastosis

19. 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

20. 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

21. anemia...impaired RBC production
 pernicious anemia
• vitamin B12 (cobalamin) deficiency
• diet, ↓intrinsic faktor (parietal gastric
cells), terminal ileum
• gross: atrophic glossitis, gastritis,
demyelinization

22. anemia...impaired RBC production
6) lack of erythropoietin
• kidney failure, parvovirosis (B19)

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

24. leukopenia
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

25. 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!

26. 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: allergic disorders, parasitic
infestation, drug reaction, certain mlg
3) thrombocytosis: infections, chronical
bleeding, tumours, iron deficiency

27. 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 secondary (radiotherapy,
alkylating agent therapy)
• bm hypercellular, ↑ erythropoiesis,
morphological changes, +/- fibrosis

28. 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

29. 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

30. CMPD
A) chronic myelogenous leukaemia
• most common
• adults, 30-60eyars
• neutrophilic leukocytosis in peripheral
blood
• Ph+ = t(9;22) = Philadelphia chr.
• bm: hypercellular (↑granulopoiesis,
↑megakaryocytes), +/- fibrosis
• extramedullary leukaemic infiltration:
spleen, liver
• → accelerated phase → blast phase

31. 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

32. CMPD
C) essential thrombocythaemia
• proliferation primarly magakaryocytic
lineage
• sustained thrombocytosis 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

33. acute leukaemias
• causes:
– complication of certain chromosomal diseases (m.
Down, Fanconi anemia, Klinefelter´s syndroma...)
– 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“)

34. 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...acute monocytic l.
 M6...acute erythroid l.
 M7...acute megakaryoblastic l.

35. acute lymphoblastic leukaemias...
histological classification
 precursor B- and T- cell lymphoblastic
leukaemia/lymphoblastic lymphoma

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

37. 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

38. 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

39. 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

40. metastasis
• osteolytic x osteoplastic
• prostate, breast, stomach, lung cancer

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

42. 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

43. transplantation
• bone marrow suppression → graft
• hypocellularity → proliferation
• immunosuppression!
• GvHD acute x chronic:
– skin, intestine, liver

44. Bleeding disorders
• cause:
• defect in the vessel wall
• platelet deficiency or dysfunction
• coagulation factors disorder

45. 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
 Marfan´s syndrome

46. bleeding disorders...vascular
2) acquired
a) avitaminosis C, ↑ corticosteroids
– cutaneous, intramuscular, mucosal bleeding
b) purpura Henoch-Schönlein
– circulating IC → skin, kidney

47. 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)

48. 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

49. 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

50. bleeding disorders...plateles
idiopathic thrombocytopenic purpura (ITP)
– autoimmune origin
– destruction in the spleen → splenectomy
– bm +/- increased megakaryopoiesis

51. bleeding disorders...plateles
2) platelet dysfunction
 adhesion disorder (Bernard-Soulier, m. von
Willebrand)
 aggregation disorder (thrombasthenia
Glanzmann)
 secretion disorder: tromboxan A2
inhibition (aspirin)

52. bleeding disorders...
coagulation factors
C) coagulation disorders
1) hereditary deficiencies
a) hemophilia A (classic hemophilia)
– f VIII (severe = activity < 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

53. 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

54. lymph vessels and nodes

55. lymphatic vessels
A) lymphoedema
• lymph is protein-rich → lymphostasis leads
to fibroproduction, +/- infectious and
ulcerative complications
1) hereditary = Milroy´s disease
• valvular disorder
2) acquired lymphoedema
• lymphoedema praecox
• secondary lymphoedema: obstruction and
lymphostasis (mlg, inflammatory changes)

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

57. lymphatic vessels
C) lymphangiitis
• lymph vessels draining the primary
(infectious) focus
• β hemolytic streptococci
• + regional lymphadenitis
• clinical: red subcutaneous line
• histology:
– lymphangiitis simplex
– lymphangiitis purulenta: pus + fibrin →
spreading → abscesses, trombophlebitis

58. 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

59. 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

60. 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

61. 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

62. 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!

63. lymph nodes...inflammation
progressive transformation of germinal
centres
– connection with HD (paragranuloma)
m. Castleman (angiofollicular hyperplasia)
– „lolly pops“ follicles
– unifocal bng x multifocal fatal

64. 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

65. lymph nodes...inflammation
m. Rosai-Dorfman (masive sinusoidal
histiocytoses)
– intrasinusoidal macrophages with
emperipolesis
d) mixed reactive hyperplasia
• etio: toxoplasmosis (epitheloid granulomas)

66. 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)

67. 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

68. 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

69. lymph nodes...neoplasms

70. 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

71. 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)

72. lymp nodes...neoplasms...NHL
2) non Hodgkin lymphomas
• predominance of neoplastic cells
• elder patients
• B and T cells

73. 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,
ENMZL=MALT, NMZL
 hairy cell leukaemia (HCL)
 diffuse large B-cell lymphoma (DLBCL)
 Burkitt lymphoma

74. chronic lymphocytic
leukaemia/small lymphocytic
lymphoma (CLL/SLL)
• elderly patients
• naive lymphocytes
• indolent type of lymphoma

75. follicular lymphoma (FCL)
• middle aged patients
• centrocytes and centroblasts
• indolent course but rellapsing!

76. mantle cell lymphoma (MCL)
• „diffuse centrocytoma“
• agressive type of lymphoma
• t(11;14) – cyklin D1

77. marginal zone lymphoma (MZL)
• mucosa associated lymphoid tissue
(MALT) – GIT, bronchi…
• association with chronic inflammation

78. diffuse large B-cell lymphoma
(DLBCL)
• „waste basket“
• transformation of small cell
lymphomas
• aggresive course x good reaction to
therapy

79. Burkitt lymphoma
• endemic x sporadic
• younger patients
• association with EBV infection

80. lymph nodes...neoplasms...B-NHL
• plasma cell neoplasms:
 monoclonal gammopathy of
undetermined significance (MGUS)
 lymphoplasmacytic lymphoma (LPL), m.
Waldenström
 plasmacytoma
 multiple myeloma

81. 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

82. anaplastic large T cell
lymphoma (ALCL)
• young patients
• typical translocation t(2;5)

83. mycosis fungoides/Sezary
syndrom
• primary skin lymphoma →
generalisation = Sezary syndrom

84. spleen

85. 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

86. spleen...regressive changes,
circulatory disorders
A) inborn anomalies
• accessory spleens = spleniculi
B) regressive changes and circulatory
disorders
1) amyloidosis
• secondary (AA)
• +/- hyposplenism

87. spleen...regressive changes,
circulatory disorders
2) storage diseases
3) hemolytic anemias
• ↑ splenic function → splenomegaly
• hereditary spherocytosis
4) chronic perisplenitis
5) splenic infarction
• white (embolization, vasculitis)
• red (thrombosis of lienal vein)

88. spleen...regressive changes,
circulatory disorders
6) chronic venosthasis
7) splenic rupture, bleeding
• traumatic

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

90. 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

91. spleen...tumours
D) tumours and pseudotumours
1) cystic formations
• posttraumatic pseudocysts
• parasitary cysts
2) hamartoma (splenoma)
• nodule
• histology: chaotic sinuses a fibrous tissue =
incorrect arrangement of the red pulp
• +/- hypersplenism

92. spleen...tumours
3) hemangioma
• histology: cavernous blood spaces,
thrombosis
4) littoral cell angioma
• phagocytosis → pancytopenia
5) inflammatory pseudotumour
• histology: inflammatory cells +
fibroproduction

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

94. thymus

95. 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

96. 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

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

98. 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

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

100. 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