A RADIOLUCENCY IN THE RAMUS OF THE MANDIBLE: WHAT IS THIS?

BACKGROUND A small radiolucent lesion is challenging for radiologists to make an accurate diagnosis, especially if it is asymptomatic and an incidental finding. It could go under the umbrella of the odontogenic or nonodontogenic cyst or tumor. We present a well-defined, corticated, expansile, unilocular radiolucency in the ramus of the mandible at the mandibular foramen level that proved to be a simple bone cyst. CASE REPORT An 18-year-old female patient presented to our clinic following referral by her orthodontist for an incidental finding of a radiolucency in the left mandibular ramus. A panoramic radiograph and cone beam computed tomography (CBCT) were taken. No changes in size were noted on panoramic radiographs 3 months apart. On CBCT, the lesion was well-defined, corticated, ellipsoidal, mildly expansile, unilocular, and uniformly radiolucent. It was located in the left ramus, below the sigmoid notch, buccal and superior to the inferior alveolar canal and displacing the canal and the mandibular foramen with dissipation of the canal wall. The medial and lateral cortices of the ramus were thinned and expanded. The findings were consistent with less aggressive, slowly growing lesions including odontogenic keratocyst, ameloblastoma, and neurovascular lesions. On surgical exploration, the lesion was devoid of any epithelial lining and was completely empty. DISCUSSION/CONCLUSIONS Simple bone cysts are nonneoplastic “pseudocysts” that are found in the mandible. Only 2% are found in the maxilla and a very small number have been reported in the condyle toward the ramus, and no radiographic images located solitary in the ramus. This is the first report showing a simple bone cyst in the middle of the ramus of the mandible.