Thymoma classification: Difference between revisions
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{{CMG}} {{AE}} {{AAM}} | {{CMG}} {{AE}} {{AAM}} | ||
==Overview== | ==Overview== | ||
In 1999, a World Health Organization Working group suggested a non-committal terminology (Masaoka classification), preserving the distinct categories of the | In 1999, a [[World Health Organization|World Health Organization (WHO)]] Working group suggested a non-committal terminology (Masaoka [[classification]]) for thymoma, preserving the distinct categories of the [[Histology|histo]]-[[Genetics|genetic]] [[classification]], by using letters and numbers to designate [[tumor]] entities. Recently, it has been very well accepted as it provides an easy comparison of [[clinical]], [[pathological]], and [[Immunology|immunological]] studies. | ||
== | ==Classification== | ||
====The World Health Organization histologic classification of thymic epithelial tumors | ====The [[World Health Organization|World Health Organization (WHO)]] [[histologic]] [[classification]] of thymic epithelial tumors is explained in the table below:<ref name="www.ncbi.nlm.nih.gov">{{Cite web | last = | first = | title = WHO histologic classification is a prognosti... [Ann Thorac Surg. 2004] - PubMed - NCBI | url = http://www.ncbi.nlm.nih.gov/pubmed/15063231 | publisher = | date = | accessdate = }}</ref>==== | ||
{| {{table}} | {| {{table}} cellpadding="4" cellspacing="0" style="border:#c9c9c9 1px solid; margin: 1em 1em 1em 0; border-collapse: collapse;" | ||
! Type | ! style="background: #4479BA; color:#FFF;" |Type | ||
! Description | ! style="background: #4479BA; color:#FFF;" |Description | ||
|- | |- | ||
| '''A''' || A tumor composed of a population of neoplastic thymic epithelial cells having spindle/oval shape, lacking nuclear atypia, and accompanied by few or no | ! style="text-align: center; padding: 5px 5px; background: #F5F5F5;" |'''A''' | ||
| style="text-align: left; padding: 5px 5px; background: #F5F5F5;" | | |||
* A [[tumor]] composed of a population of [[Cancer|neoplastic]] [[Thymus|thymic]] [[Epithelium|epithelial]] [[Cell (biology)|cells]] having spindle/oval shape, lacking [[Atypia|nuclear atypia]], and accompanied by few or no non-[[neoplastic]] [[Lymphocyte|lymphocytes]] | |||
|- | |- | ||
| '''AB''' || A tumor in which foci having the features of type A thymoma are admixed with foci rich in lymphocytes | ! style="text-align: center; padding: 5px 5px; background: #F5F5F5;" |'''AB''' | ||
| style="text-align: left; padding: 5px 5px; background: #F5F5F5;" | | |||
* A [[tumor]] in which foci having the features of type A thymoma are admixed with foci rich in [[Lymphocyte|lymphocytes]] | |||
|- | |- | ||
| '''B1''' || A tumor that resembles the normal functional thymus in that it combines large expanses having an appearance practically indistinguishable from normal thymic cortex with areas resembling thymic medulla | ! style="text-align: center; padding: 5px 5px; background: #F5F5F5;" |'''B1''' | ||
| style="text-align: left; padding: 5px 5px; background: #F5F5F5;" | | |||
* A [[tumor]] that resembles the normal functional [[thymus]] in that it combines large expanses having an appearance practically indistinguishable from normal [[Thymus|thymic cortex]] with areas resembling [[Thymus|thymic medulla]] | |||
|- | |- | ||
| '''B2''' || A tumor in which the neoplastic epithelial component appears as scattered plump cells with vesicular nuclei and distinct nucleoli among a heavy population of lymphocytes. Perivascular spaces are common and sometimes very prominent. A perivascular arrangement of tumor cells resulting in a palisading effect may be seen | | style="text-align: center; padding: 5px 5px; background: #F5F5F5;" |'''B2''' || style="text-align: left; padding: 5px 5px; background: #F5F5F5;" | | ||
* A [[tumor]] in which the [[Cancer|neoplastic]] [[Epithelium|epithelial]] component appears as scattered plump [[Cell (biology)|cells]] with [[Vesicle (biology)|vesicular]] [[Cell nucleus|nuclei]] and distinct [[Nucleolus|nucleoli]] among a heavy population of [[Lymphocyte|lymphocytes]]. | |||
* Perivascular spaces are common and sometimes very prominent. | |||
* A perivascular arrangement of [[Tumor cell|tumor cells]], resulting in a palisading effect, may be seen | |||
|- | |- | ||
| '''B3''' || A type of thymoma predominantly composed of epithelial cells having a round or polygonal shape and exhibiting no or mild atypia | | style="text-align: center; padding: 5px 5px; background: #F5F5F5;" |'''B3''' || style="text-align: left; padding: 5px 5px; background: #F5F5F5;" | | ||
* A type of thymoma predominantly composed of [[epithelial cells]] having a round or polygonal shape and exhibiting no or mild [[atypia]] | |||
* They are admixed with a mild component of [[lymphocytes]], resulting in a sheet-like growth of the [[neoplastic]] [[epithelial cells]] | |||
|- | |- | ||
| '''C''' || A thymic tumor (thymic carcinoma) exhibiting clear-cut cytologic atypia and a set of cytoarchitectural features no longer specific to the thymus, but rather analogous to those seen in carcinomas of other organs. Type C thymomas lack immature lymphocytes; whatever lymphocytes may be present are mature and usually admixed with plasma cells | | style="text-align: center; padding: 5px 5px; background: #F5F5F5;" |'''C''' || style="text-align: left; padding: 5px 5px; background: #F5F5F5;" | | ||
* A [[Thymus|thymic]] [[tumor]] ([[Thymus|thymic]] [[carcinoma]]) exhibiting clear-cut [[Cell biology|cytologic]] [[atypia]] and a set of cytoarchitectural features no longer specific to the [[thymus]], but rather analogous to those seen in [[Carcinoma|carcinomas]] of other [[Organ (anatomy)|organs]]. | |||
* Type C thymomas lack immature [[Lymphocyte|lymphocytes]]; whatever [[Lymphocyte|lymphocytes]] may be present are mature and usually admixed with [[Plasma cell|plasma cells]] | |||
|- | |- | ||
|} | |} | ||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
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[[Category:Rare diseases]] | [[Category:Rare diseases]] | ||
[[Category:Disease]] | [[Category:Disease]] | ||
[[Category:Up-To-Date]] | |||
[[Category:Oncology]] | |||
[[Category:Medicine]] | |||
[[Category:Hematology]] | |||
[[Category:Immunology]] | |||
[[Category:Surgery]] | |||
Latest revision as of 20:33, 8 August 2019
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Thymoma Microchapters |
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Diagnosis |
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Case Studies |
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Thymoma classification On the Web |
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American Roentgen Ray Society Images of Thymoma classification |
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Risk calculators and risk factors for Thymoma classification |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]
Overview
In 1999, a World Health Organization (WHO) Working group suggested a non-committal terminology (Masaoka classification) for thymoma, preserving the distinct categories of the histo-genetic classification, by using letters and numbers to designate tumor entities. Recently, it has been very well accepted as it provides an easy comparison of clinical, pathological, and immunological studies.
Classification
The World Health Organization (WHO) histologic classification of thymic epithelial tumors is explained in the table below:[1]
| Type | Description |
|---|---|
| A |
|
| AB |
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| B1 |
|
| B2 |
|
| B3 |
|
| C |
|