SMARCB1 and chordoma: Differently from most of atypical teratoid/rhabdoid tumors, in chordomas, loss of SMARCB1/INI1 expression at immunohistochemistry results from a homozygous deletion of the SMARCB1 gene (4, 9, 25), and has been reported not only in poorly differentiated variants (in which it represents a diagnostic hallmark) (4, 6, 9, 26, 27), but also in a case of conventional chordoma with transformation to poorly differentiated chordoma (17), and in another case of conventional chordoma with dedifferentiated sarcomatous components (28).