Potentially actionable FGFR2 high-level amplification in thymic sebaceous carcinoma

Abstract

Our aim was to investigate sebaceous differentiation in thymus tumours and to identify new actionable genomic alterations. To this end we screened 35 normal and 23 hyperplastic thymuses, 127 thymomas and 41 thymic carcinomas for the presence of sebaceous differentiation as defined by morphology and expression of adipophilin and androgen receptor (AR). One primary thymic carcinoma showed morphology of sebaceous carcinomas (keratinizing and foam cells, calcifications, giant cells), a strong expression of adipophilin and AR together with squamous markers. NGS revealed high-level amplification of fibroblast growth factor receptor 2 (FGFR2). In thymuses and thymomas, no cells with sebaceous morph..