Hard Palate Masses: Differential Diagnosis with CT and MR

ABSTRACT

PURPOSE: To determine the differential points of hard palate masses, using CT and MR. MATERIALS AND METHODS: MR (N=18) and CT (N=15) findings in 30 patients with pathologically-proven hard palate masses were reviewed. Masses originating in minor salivary glands were the most common (66.7%, N=20), and the remainder were accounted for by squamous cell carcinoma (N=5), lymphoma (N=2), malignant schwannoma (N=1), neurofibroma (N=1), and cholesterol granuloma (N=1). Location and demarcation of the lesions, MR signal intensity, degree of enhancement, internal architecture, and the patterns of adjacent tissue plane invasion were analyzed. RESULTS: The location of lesions originating in minor salivary glauds was as follows paramedial, 73.7% (14/19); midline, 85.7% (6/7); and marginal,0% (0/4). On MR imaging, signal intensity and degree of enhancement showed no significant differential point except lower T2 signal intensity (3/5) and less enhancement (4/5) in squamous cell carcinoma than in other masses. Necrosiswas seen in 10/21 malignant masses (47.6%), poor demarcation in 10/21 (47.6%), bone invasion in 19/21 (90.5%), and tissue plane invasion in 15/21 (71.4%); in benign masses, the corresponding figures were 4/9 (44.4%), 1/9 (11.1%), 2/9 (22.2%), and 3/9 (33.3%). Two of 21 malignant masses (9.5%) showed none of the above charachteristics. CONCLUSION: Centrally located lesions most probably originate in minor salivary glands. In the hard palate, benign masses can show features which are generally thought to be those of malignant tumors, whereas malignant tumors can be free of such features; in differential diagnosis, caution is therefore required.