A case of undifferentiated high-grade pleomorphic sarcoma arising in the mandible

Undifferentiated high-grade pleomorphic sarcoma （UHPS） is a highly malignant tumor that has polymorphisms but does not show specific differentiation. We report a very rare case of UHPS occurring in the mandible. A 66-year-old woman was referred to our hospital complaining of paresthesia of the right mental region. A soft elastic mass of 2 cm diameter was palpable in the right cheek. There were no abnormal findings in panoramic radiography except for bone absorption around the crown of an impacted mandibular third molar. CT images revealed a 2-cm contrast-enhanced mass lesion in the proximity of the anterior border of the mandibular ramus, with moth-eaten type bone destruction. On MR images, the signal in the bone marrow of the ascending ramus of the mandible was decreased on T1-weighted images. Hemimandibulectomy, right neck dissection, and reconstruction using a pectoralis major myocutaneous flap were performed under the diagnosis of sarcoma. The excised tumor specimen was diagnosed as undifferentiated high-grade pleomorphic sarcoma. There has been no sign of recurrence or metastasis for 1 year and 2 months postoperatively.