This included a germ cell tumor in 12 (30%) patients by the finding of i(12p), increased 12p copy number, or a deletion of the long arm of chromosome 12.
One or more copies of i(12p), excess 12p copy number, or a deletion on the long arm of chromosome 12 was found in seven of 28 (25%) midline tumors of uncertain histogenesis, thus establishing a diagnosis of a germ cell tumor in these patients.
Clonal relationship between the teratoma and rhabdomyosarcoma of the germ cell tumor was established by the presence in both of i(12p), the characteristic marker of germ cell tumors.