We report a case of intraosseous lipomas arising in the mandible. A 68-year-old man was referred to our department for evaluation of a radiolucent lesion in the right side of the mandible. The face was symmetric. No swelling of cervical lymph nodes or hyposthesia of the right lower lip was noted. The oral mucous membrane was normal despite many residual roots, and no bone eminence was palpable in the right side of the mandible. Panoramic radiography and computed tomography revealed a unilocular radiolucent lesion measuring 30 x 20 mm at the border of the right side of the mandible. On magnetic resonance imaging, the lesion showed signal intensity as high as that of fat tissue on T1- and T2-weighted images, and the signal intensity was reduced by fat suppression on T2-weighted images. The lesion was diagnosed as an intraosseous lipoma in the mandible and was extirpated via a submandibular approach with the patient under general anesthesia. The surgical specimen was elastic soft and yellowish. Histologically, the lesion consisted of proliferation of lobulated mature adipocytes. Degeneration of adipocytes and fibrosis and calcification were partly observed within the lesion. Nuclear atypia suggesting malignancy was not noted. On the basis of these findings, the lesion was histologically diagnosed to be a lipoma. The postoperative course has been uneventful, with no evidence of recurrence 2 years 10 months after surgery.
