The opacified maxillary sinus: CT findings in chronic sinusitis and malignant tumors.

To distinguish opacification owing to inflammatory conditions (sinusitis) from that caused by nasomaxillary malignancy, computed tomography scans in 24 proved cases of sinusitis or tumor were reviewed for features related to sinus size, wall thickness, and character of bone erosion. An anatomic system was defined for classifying lesions according to the surface and type of bony involvement. In 12 cases of chronic maxillary sinusitis, the involved sinus was usually small and thick walled. The nasal surface of the involved sinus usually was eroded; often the orbital surface was eroded. The erosion was, however, short, irregular, and in the region of a normal dehiscence (semilunar hiatus or infraorbital canal) in all cases. The infratemporal surface was never eroded. In 12 cases of nasomaxillary neoplasia, the sinus was enlarged, one or more walls of the involved sinus being thinned and expanded. Bone erosion was present in all cases; erosion of the infratemporal surface was specific for neoplasia and significant as the usual site of recurrence.