A case of primary intraosseous carcinoma related impacted lower third molar

Abstract

We report a case of primary intraosseous carcinoma （PIOC） of the jaw thought to be related to the crown of an impacted mandibular third molar in a 74-year-old man that was detected during a routine checkup at his family dental clinic. He was referred to our department with paresthesia affecting the right lower lip and occlusal pain in the right mandibular molar region. The right lower second molar was elongated with grade 2 mobility and the buccal gingiva was mildly swollen. There was no purulent discharge. Panoramic radiographs showed an ill-defined radiolucent lesion measuring 35×25 mm with irregular margins that was continuous with the crown of an inverted and impacted right mandibular third molar. A biopsy specimen was obtained. The histopathological diagnosis was squamous cell carcinoma （with suspicion of PIOC）. The patient underwent submandibular dissection, segmental resection of the mandible, and reconstruction of the jaw with a metal plate. PIOC is generally associated with malignant transformation of a cystic lesion. However, there were no abnormal findings on panoramic radiographs taken at his family dental clinic 8 months earlier in this case. Therefore, it is probable that the malignancy had developed without cystic changes and had increased rapidly in size. Although asymptomatic impacted mandibular third molars and periodontitis are common, dentists should keep various lesions including PIOC in mind in elderly patients despite the low risk of developmental cysts.