Expression oF C-KIT (CD 117) in Epithelial Thymic Malignancies

ABSTRACT Study objectives The expression of c-kit (CD117) was investigated to evaluate its usefulness as a marker supporting differential diagnosis and choice of therapy. In thymic epithelial tumors the expression of c-kit may explain a new model of tumor biology, and support the use of determinate target therapy as a new optional approach. Methods We examined the immunohistochemical expression of c-kit in 28 cases of thymic epithelial tumors diagnosed in our department between 2003-2010, that had been classified on the basis of the World Health Organization histologic classification system: 24 thymoma and 4 thymic carcinoma (1 type A, 4 type AB, 1 type B1, 12 type B2, 6 type B3 and 4 type C). Results c-kit expression showed immunoreactivity positive in 18% of the all cases (5 patients). In this subgroup, 1 type B2, 1 type B3 and 3 type C. In contrast no immunoreactivity was found in the thymoma cases (types A, AB and B1). No differences were found in the c-kit expressing group between the genders (12 females, 16 males). All c-kit expressing cases were older than 61 years old. Conclusion Expression of c-kit is an immunohistochemical marker for the diagnosis of thymic carcinoma, and represent a new model of tumor biology with potential development of new targeted therapies as an option for the treatment of thymic carcinoma on the basis of the kit pathways. Clinical trials are necessary to demonstrate the efficacy of these new theoretical strategies. Disclosure All authors have declared no conflicts of interest.