The Principles of Clinical Cytogenetics - Extra Materials - Springer

Cytogenetics of Solid Tumors 435
Fig. 5. Karyotype of a malignant mesothelioma in which arrows indicate rearrangements resulting in loss of
material from the short arms of chromosomes 1 and 3 and from the long arm of chromosome 22.
to chemotherapy and can even undergo spontaneous regression, and from a cytogenetic standpoint,
they have near-triploid karyotypes without 1p deletion or N-MYC amplification (117). The second
group includes tumors with near-diploid or near-tetraploid karyotypes, 1p deletion, and, in many
cases, N-MYC amplification (see Fig. 6) (118). N-MYC amplification, typically manifested as double
minute chromosomes, is arguably the most ominous of the adverse prognostic markers. In children,
N-MYC amplified neuroblastomas are rarely curable, although complete remissions can sometimes
be obtained using intensive myeloablative chemotherapy. Therefore, genetic analyses can be useful
adjuncts in determining appropriate intensity of therapy, particularly for those children whose prognoses
are not clear based on clinical parameters (118). Cytogenetic analyses of neuroblastoma have
been difficult, however, because the tumor cells from most favorable prognosis neuroblastomas fail
to divide in culture (118). On the other hand, N-myc amplification and chromosome 1 deletions can
be demonstrated in interphase cells by FISH (119,120).
Rhabdoid Tumors
Most malignant rhabdoid tumors, whether arising in soft tissues, kidney, or the central nervous
system, have deletions of the long arm of chromosome 22. The chromosome 22 deletions target a