RT Journal Article
SR Electronic
T1 Expression of thymoproteasome subunit β5t in type AB thymoma
JF Journal of Clinical Pathology
JO J Clin Pathol
FD BMJ Publishing Group Ltd and Association of Clinical Pathologists
SP 276
OP 278
DO 10.1136/jclinpath-2013-201930
VO 67
IS 3
A1 Yosuke Yamada
A1 Utano Tomaru
A1 Akihiro Ishizu
A1 Takayuki Kiuchi
A1 Masanori Kasahara
A1 Yoshihiro Matsuno
YR 2014
UL http://jcp.bmj.com/content/67/3/276.abstract
AB Type AB thymoma is a thymic epithelial tumour composed of lymphocyte-poor type A and lymphocyte-rich type B components. Although it is categorised as a single entity in the classification of WHO, it shows a broad range of morphology. To investigate whether the functional characteristic of neoplastic cells in type AB thymoma relates to morphological diversity, we performed immunohistochemical analysis using anti-β5t antibody in 20 cases of type AB thymoma. β5t is a recently discovered proteasomal β subunit expressed exclusively in cortical thymic epithelial cells and tumour epithelial cells of thymomas with cortical differentiation. Consistent with our previous observation, β5t was predominantly expressed in the type B component. When the type B component was divided into three groups morphologically, β5t was expressed more frequently in cases with round to polygonal than spindle to oval tumour cells. Furthermore, the ratio of terminal deoxynucleotidyl transferase (TdT)-positive lymphocytes was increased in components with higher expression of β5t. These results indicate that the histological diversity of type AB thymoma correlates with expression of a functional marker β5t and abundance of TdT-positive lymphocytes.