Solitary fibrous tumor.

First described as a pleural neoplasm, the solitary fibrous tumor has been reported in a number of extrapleural sites, including the upper respiratory tract. The neoplasm is of mesenchymal origin, exists in benign and malignant forms, and is a histopathologic diagnosis made after exclusion of other soft tissue neoplasms. None of the eight reported sinonasal and nasopharyngeal solitary fibrous tumors have been histologically or biologically malignant. Surgical excision appears to control the tumor at these sites.