A Review of the Role of Cytogenetics in the Diagnosis of Orbital Rhabdomyosarcoma

Abstract

Rhabdomyosarcoma (RMS) is the most common sarcoma of childhood and adolescence. Approximately 10% arise in the orbit, where the embryonal type is most common variant. The alveolar variant is less frequent and has a worse prognosis. Cytogenetic studies have revealed that most alveolar rhabdomyosarcomas have translocations involving the PAX and the FOX01 genes, giving rise to fusion genes that contribute to lack of differentiation and proliferation of the tumor cells. However, approximately 20% of alveolar rhabdomyosarcomas lack translocations and have been found to behave more similarly to embryonal cases. Histopathology remains the basis of diagnosis, but cytogenetic features and molecular signatures are becoming part of the routine analysis of RMS, since they determine not only prognosis, but also management and treatment regimens. A comprehensive review of the recent published literature in relation to orbital rhabdomyosarcomas and their cytogenetic features as well as clinical and therapeutic implications will be discussed.

Keywords: FOX01; PAX3; PAX7; Rhabdomyosarcoma; alveolar rhabdomyosarcoma; chimeric fusion genes; chimeric protein; embryonal rhabdomyosarcoma; review article.