Undifferentiated sarcoma of the sphenoid sinus.

Paranasal sinuses sarcomas are rare and no treatments have been established. We report a young-adult case of sphenoid sinus sarcoma treated by carbon-ion radiotherapy. The patient presented with progressive left-sided visual impairment. A tumor was then identified and partial resection by transnasal approach was performed. The resected mass showed typical morphology of mesenchymal tumor, and morphological and molecular analyses ruled out a predominant-differentiation phenotype. The pathological diagnosis was undifferentiated sarcoma. The residual lesion was treated with carbon-ion radiotherapy, and tumor progression was absent for one year. The patient died of the tumor regrowth 20 months after initial diagnosis. Although this case had a poorer outcome compared with cases of the more-common sarcoma types, our experience suggested that carbon-ion radiotherapy is potentially beneficial in unresectable undifferentiated sarcomas cases of sphenoid sinus.