Radiation-induced Leiomyosarcoma of the Oral Cavity: A Rare Occurrence Detected on 18F-FDG PET/CT.

Radiation-induced sarcomas (RIS) or postirradiation sarcomas have been reported as a rare long-term complication of radiation therapy (RT). The survival benefit offered by radiotherapy has been masked by an increase in the incidence of these sarcomas, thus making radiotherapy a double-edged sword. RIS generally develop with a mean latency period of 10-15 years and encompass different histological types. We report a case of oral leiomyosarcoma with a rather short latency period of 4 years after the radiotherapy of the prior oral squamous cell carcinoma (OSCC) detected on fluorine-18 (18F)-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT). The rarity of occurrence of leiomyosarcoma in the oral cavity is also highlighted.