Thymoma pathophysiology
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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
Origin
- It has been believed that thymic epithelium is derived from both ectodermal and endodermal stem cells.
- Recent evidence indicates that epithelial populations originate from a common progenitor of endodermal origin.
- Occurrence of more differentiated “committed stem cells” with medullary, cortical or other phenotypes is possible.[1][2]
Microscopic Pathology
On microscopic histopathological analysis, round cells, with ample vacuolated cytoplasms, and fat droplets are characteristic findings of thymoma.
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Gross Pathology
On gross pathology, a well circumscribed mass, that is locally invasive is a characteristic finding of thymoma.
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Genetic Features
Genetic alterations reported for the different WHO histological thymoma subtypes[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
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Associated Disorders
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 cytopenis: eosinophils,basophils, neutrophils, Immunodeficiencies: hypogammaglobulinaemia +/- T-cell deficiencies (Good syndrome) |
| Dermatologic 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
- ↑ Blackburn, CC.; Manley, NR.; Palmer, DB.; Boyd, RL.; Anderson, G.; Ritter, MA. (2002). "One for all and all for one: thymic epithelial stem cells and regeneration". Trends Immunol. 23 (8): 391–5. PMID 12133801. Unknown parameter
|month=ignored (help) - ↑ Gill, J.; Malin, M.; Holländer, GA.; Boyd, R. (2002). "Generation of a complete thymic microenvironment by MTS24(+) thymic epithelial cells". Nat Immunol. 3 (7): 635–42. doi:10.1038/ni812. PMID 12068292. Unknown parameter
|month=ignored (help) - ↑ "http://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb10/BB10.pdf" (PDF). Retrieved 26 February 2014. External link in
|title=(help) - ↑ "http://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb10/BB10.pdf" (PDF). External link in
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