Imaging modalities to access bony tumors and hyperplasic reactions of the temporomandibular joint.

Benign and malignant tumors in the temporomandibular joint (TMJ) are rare. However, when a patient presents with clinical findings such as altered occlusion or facial asymmetry, a morphologic alteration in the condyle should be ruled out. The differential diagnosis for benign hyperplastic bony lesions in the TMJ should include condylar hyperplasia, osteochondroma, osteoma, chondroma, and osteoblastoma. If malignant features are present, chondrosarcoma and osteosarcoma should be considered. For the differential diagnosis, imaging is the most noninvasive method to evaluate the integrity of the TMJ. Imaging can be classified as morphologic or functional according to the information provided. The current scientific data have shown that panoramic images have 97% sensitivity and 45% specificity for identifying hyperplastic conditions in the TMJ. The sensitivity and specificity of medical computed tomography (CT) and cone-beam CT is 70% and 100%, and 80% and 100%, respectively, for the detection of bony abnormalities. To differentiate benign and malignant bony tumors, magnetic resonance imaging has a sensitivity and specificity of 44% and 95%, respectively. The corresponding percentages for single positron emission CT are 91% and 94%, for single positron emission CT/CT are 100% and 100%, for positron emission tomography are 88% and 72%, and for positron emission tomography/CT are 100% and 97%. The combination of morphologic and functional (single positron emission CT and positron emission tomography) modalities appears to improve the sensitivity and specificity to assess a hyperplastic condyle, facilitating treatment planning and providing a better prognosis for the patient.