Difference between revisions of "Thymoma pathophysiology"

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==Pathophysiology==
 
==Pathophysiology==
===Origin===
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*It has been believed that thymic epithelium is derived from both [[ectoderm]]al and [[endoderm]]al stem cells.
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=== Physiology ===
*Recent evidence indicates that epithelial populations originate from a common progenitor of endodermal origin.
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*Occurrence of more differentiated “committed stem cells” with medullary, cortical or other phenotypes is possible.<ref name="Blackburn-2002">{{Cite journal  | last1 = Blackburn | first1 = CC. | last2 = Manley | first2 = NR. | last3 = Palmer | first3 = DB. | last4 = Boyd | first4 = RL. | last5 = Anderson | first5 = G. | last6 = Ritter | first6 = MA. | title = One for all and all for one: thymic epithelial stem cells and regeneration. | journal = Trends Immunol | volume = 23 | issue = 8 | pages = 391-5 | month = Aug | year = 2002 | doi =  | PMID = 12133801 }}</ref><ref name="Gill-2002">{{Cite journal  | last1 = Gill | first1 = J. | last2 = Malin | first2 = M. | last3 = Holländer | first3 = GA. | last4 = Boyd | first4 = R. | title = Generation of a complete thymic microenvironment by MTS24(+) thymic epithelial cells. | journal = Nat Immunol | volume = 3 | issue = 7 | pages = 635-42 | month = Jul | year = 2002 | doi = 10.1038/ni812 | PMID = 12068292 }}</ref>
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* Thymus is the site of maturation of T cells.
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* This makes thymus the primary center of adaptive immunity.
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=== Pathogenesis ===
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* The exact pathogenesis of the primary tumor development is not well understood.
 +
 
 +
* Primary tumors of thymus are relatively rare.
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* Thymoma is the most common type of primary tumor of thymus.
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* Thymoma is histologically comprised of abnormally conditioned T cells.
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* The mingling of these abnormal T cells into the circulation is believed to be involved in the associated autoimmune disorders.<ref>{{Cite journal
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  | author = [[C. Buckley]], [[D. Douek]], [[J. Newsom-Davis]], [[A. Vincent]] & [[N. Willcox]]
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| title = Mature, long-lived CD4+ and CD8+ T cells are generated by the thymoma in myasthenia gravis
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| journal = [[Annals of neurology]]
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| volume = 50
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| issue = 1
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| pages = 64–72
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| year = 2001
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| month = July
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  | pmid = 11456312
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}}</ref><ref>{{Cite journal
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  | author = [[J. V. Souadjian]], [[P. Enriquez]], [[M. N. Silverstein]] & [[J. M. Pepin]]
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| title = The spectrum of diseases associated with thymoma. Coincidence or syndrome?
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| journal = [[Archives of internal medicine]]
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| volume = 134
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| issue = 2
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| pages = 374–379
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| year = 1974
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| month = August
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| pmid = 4602050
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}}</ref>
  
 
===Microscopic Pathology===
 
===Microscopic Pathology===

Revision as of 00:36, 16 August 2019

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Amr Marawan, M.D. [2] Ahmad Al Maradni, M.D. [3]

Overview

  • On gross pathology, a well circumscribed mass that is locally invasive is a characteristic finding of thymoma.
  • On microscopic histopathological analysis, round cells, with ample vacuolated cytoplasms, and fat droplets are characteristic findings of thymoma.

Pathophysiology

Physiology

  • Thymus is the site of maturation of T cells.
  • This makes thymus the primary center of adaptive immunity.

Pathogenesis

  • The exact pathogenesis of the primary tumor development is not well understood.
  • Primary tumors of thymus are relatively rare.
  • Thymoma is the most common type of primary tumor of thymus.
  • Thymoma is histologically comprised of abnormally conditioned T cells.
  • The mingling of these abnormal T cells into the circulation is believed to be involved in the associated autoimmune disorders.[1][2]

Microscopic Pathology

On microscopic histopathological analysis, round cells, with ample vacuolated cytoplasms, and fat droplets are characteristic findings of thymoma.

Gross Pathology

On gross pathology, a well circumscribed mass that is locally invasive is a characteristic finding of thymoma.

Genetic Features

Genetic alterations reported for the different WHO histological thymomasubtypes[3]

WHO Type Chromosomal Gains Chromosomal Losses
Type A none -6p
Type AB none -5q21-22,-6q,-12p,-16q
Type B3 +1q -6,-13q

Video

Associated Disorders

Approximately 30% of patients have their thymomas discovered because they have an associated autoimmune disorder. These disorders include:[4]

Type Diseases
Neuromuscular Diseases Myasthenia gravis, neuromyotonia, rippling muscle disease, polymyositis/dermatomyositis, encephalitis (limbic, cortical and brain stem), intestinal pseudoobstruction
Haematologic Autoimmune Diseases Anemia: pure red cell aplasia, pernicious anemia, hemolytic anemia, aplastic anemia. Other isolated cytopenia: eosinophils,basophils, neutrophils, immunodeficiencies: hypogammaglobulinaemia +/- T-cell deficiencies (Good syndrome)
Dermatologies Diseases Pemphigus (foliaceus or paraneoplastic), lichen planus, alopecia areata
Endocrine Disorders Addison disease, graves disease, Cushing's disease
Renal and Hepatic Diseases Glomerulonephritis, autoimmune hepatitis
Systemic Autoimmune Diseases SLE, Sjögren's syndrome, systemic sclerosis, graft-versus-host disease

References

  1. C. Buckley, D. Douek, J. Newsom-Davis, A. Vincent & N. Willcox (2001). "Mature, long-lived CD4+ and CD8+ T cells are generated by the thymoma in myasthenia gravis". Annals of neurology. 50 (1): 64–72. PMID 11456312. Unknown parameter |month= ignored (help)
  2. J. V. Souadjian, P. Enriquez, M. N. Silverstein & J. M. Pepin (1974). "The spectrum of diseases associated with thymoma. Coincidence or syndrome?". Archives of internal medicine. 134 (2): 374–379. PMID 4602050. Unknown parameter |month= ignored (help)
  3. "http://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb10/BB10.pdf" (PDF). Retrieved 26 February 2014. External link in |title= (help)
  4. "http://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb10/BB10.pdf" (PDF). External link in |title= (help)

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