Expression of cathepsins V and S in thymic epithelial tumors.

Human pathology 2017 Feb

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Cathepsins are a group of proteolytic enzymes of the endosomal/lysosomal pathway involved in the thymic development of T cells restricted by major histocompatibility complex class II molecules. In the normal thymus, cathepsin V (CTV) and cathepsin S (CTS) are expressed in cortical and medullary epithelial cells, respectively. To investigate whether cathepsins could serve as a diagnostic marker, we performed immunohistochemical analysis for CTV and CTS in 77 cases of thymic epithelial tumors. Almost all cases (59/60) of thymoma expressed CTV, whereas 28 of 60 cases of thymoma expressed CTS. Notably, CTS was expressed in most cases of type A and type AB thymomas, but not in type B thymoma. The expression of cathepsins in type AB thymoma showed a clear correlation with histologic features; CTV was found predominantly in the type B component, and CTS was frequently expressed in the type A component. In thymic carcinoma, CTV was expressed in less than half cases (7/17), and the ratio of CTS-positive cases was equivalent to that of thymoma (8/17). Cases of CTV-negative thymic carcinoma tended to have a higher incidence of recurrence than did CTV-positive cases. Although further studies with a larger number of cases are required to confirm the utility of cathepsin immunostaining, CTV and CTS appear to serve as auxiliary diagnostic and/or prognostic markers in thymic epithelial tumors. Copyright © 2016 Elsevier Inc. All rights reserved.

Citation

Shizuka Kiuchi, Utano Tomaru, Akihiro Ishizu, Makoto Imagawa, Takayuki Kiuchi, Sari Iwasaki, Akira Suzuki, Noriyuki Otsuka, Takahiro Deguchi, Tomohiro Shimizu, Katsuji Marukawa, Yoshihiro Matsuno, Masanori Kasahara. Expression of cathepsins V and S in thymic epithelial tumors. Human pathology. 2017 Feb;60:66-74