Tumors of the peripheral nervous system include neuroblastomas,
pheochromocytomas, and neuroepitheliomas.
Neuroblastomas and pheochromocytomas are adrenergic in
origin and share certain genetic features, whereas
neuroepitheliomas are thought to be cholinergic and are
characterized by distinct genetic features. Neuroblastomas
are characterized by deletion of the short arm of chromosome
1 (lp), amplification of the N-myc proto-oncogene,
and hyperdiploidy in subsets of tumors. All three of these
genetic features have prognostic value in subsets of patients.
Allelic loss of 14q also occurs with increased frequency, but
the prognostic importance of this abnormality is not known
yet. Pheochromocytomas have not been studied as extensively,
but allelic loss for 1 p appears to be a frequent change,
and no clear examples of oncogene activation have been
identified. Neuroepitheliomas are characterized by translocation
between chromosomes 11 and 22. Although they
have a characteristic pattern of proto-oncogene expression,
it is not clear that any of these oncogenes are activated
specifically, and no sites of allelic loss have been identified
to date. Thus, cytogenetic and molecular analysis of neuroblastomas,
pheochromocytomas, and neuroepitheliomas is
useful in distinguishing them from each other and from other
tumors in selected cases. Furthermore, certain genetic markers
help predict a tumor's clinical behavior, especially for
neuroblastoma