Osteocartilaginous tumors in the parapharyngeal space arising from bone exostoses.

Three osteocartilaginous tumors that arose from bone stalks were diagnosed by the demonstration, on multiplanar cross-sectional CT and MR images, of the site of stalk attachment to the adjacent mandible (one), skull base (one), and cervical vertebra (one). All three patients presented with signs and symptoms related to mass effect in the parapharyngeal region. Mass effect was more pronounced in the two cases of malignant degeneration (osteosarcoma, chondrosarcoma) than in the single case of benign osteocartilaginous exostosis. Differentiation of benign from malignant osteocartilaginous tumor may be accomplished by appreciating characteristic CT and MR features of the cartilage cap. The differential diagnosis of mass lesions of the parapharyngeal space should include tumors of osteocartilaginous origin.