FISH identification of i(12p) and/or 12p overrepresentation in routinely processed surgical specimens is a useful ancillary diagnostic tool in distinguishing testicular epidermoid cysts from teratoma.
Furthermore, the findings of i(12p) in both the teratomatous and nonteratomatous components of ovarian mixed GCTs supports that the teratoma derives from other components, similar to the situation in the testis.
A detailed karyotype analysis using fluorescence in situ hybridization (FISH), with 24 chromosome-specific paint probes has been carried out on newly established cell lines from two testicular tumors, an i(12p)-positive teratoma, and an i(12p)-negative combined seminoma/teratoma.
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.