Which histologic findings are characteristic of thymoma?

Updated: Dec 03, 2018
  • Author: Kendrix J Evans, MD, MS; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Answer

Traditionally, thymomas have been classified into three histologic types according to the cell type that is predominant—lymphocytic, epithelial, or lymphoepithelial. A pathologic classification was developed by the World Health Organization (WHO). In a study conducted in Japan between 1973 and 2001 of a series of 100 resected thymomas, prognostic categories were distinguished by using this WHO classification (see Table 2 below). [6]

Table 2. World Health Organization (WHO) Pathologic Classification and Associated Prognostic Categories (Open Table in a new window)

Type

Histologic Description

Disease-Free Survival at 10 years,* %

A

Medullary thymoma

100

AB

Mixed thymoma

100

B1

Predominantly cortical thymoma

83

B2

Cortical thymoma

83

B3

Well-differentiated thymic carcinoma

35

C

Thymic carcinoma

28

*Series of 100 thymomas resected in Japan between 1973 and 2001 using WHO classification. [6]


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