Stage IV primitive-appearing sinus and orbital rhabdomyosarcoma presenting in a 68-year-old female previously treated for breast cancer.

A 68-year-old female who had undergone treatment several years previously for breast cancer presented with diplopia and unilateral proptosis and exposure keratopathy related to biopsy-proven rhabdomyosarcoma of the sinus and orbit. Further evaluation revealed multiple metastatic lesions felt to have originated from the primary sinus and orbital tumor. Histopathologic examination showed primitive-appearing rhabdomyosarcoma with some features suggestive of the alveolar subtype. Orbital or sinus rhabdomyosarcoma is seen almost exclusively in the pediatric population, but may very rarely occur in adults. There are several genetic mutations that appear to play a role in both rhabdomyosarcoma and certain breast tumors. There is also increasing evidence that even low doses of radiation may contribute to the future development of cancer, particularly in susceptible individuals. In our patient with atypical demographics for rhabdomyosarcoma, the previous neoplasm and treatment thereof may have predisposed to the development of this rare tumor.