SMARCB1 and chordoma: Poorly differentiated chordoma is a rare histotype arising mainly in children and young adults and composed of nests of mitotically active epithelioid cells with scattered intracytoplasmic vacuoles lacking physaliphorous cell morphology and extracellular myxoid stroma and characterized by SMARCB1 homozygous deletion and loss of INI1 expression [3,4,5].