Sacrococcygeal chordomas in patients with tuberous sclerosis complex show somatic loss of TSC1 or TSC2

Chordomas are rare sacrococcygeal/sacral, sphenooccipital/clivus, and spinal tumors whose molecular etiology remains relatively understudied. As several anecdotal reports had described chordomas in individuals with tuberous sclerosis complex (TSC), a multisystem hamartoma syndrome, we hypothesized that the genes that cause TSC may have an etiological role in chordomas. In two cases of sacrococcygeal chordomas in individuals with TSC, one with a germ-line TSC2 mutation and the other with a germ-line TSC1 mutation, we confirmed somatic inactivation of the corresponding wild-type allele by loss of heterozygosity analysis and immunohistochemistry. These data provide the first evidence of a pathogenic role by TSC genes in sacrococcygeal chordomas.