Parosteal osteogenic sarcoma of the mandible, Existence masked by diffuse periodontal inflammation.

A 38-year-old man was in a state of poor oral hygiene, with multiple broken carious teeth and diffuse inflammatory hyperplasia of the gingival tissues. A mandibular, alveolar soft tissue mass in the premolar-molar region was noted on the right side, in continuity with the gingival hyperplasia. Biopsy of the lesion ruled out a diagnosis of squamous cell carcinoma. The patient underwent extraction of his teeth, and all hyperplastic tissues including the tumefaction were excised. Five months later, the patient had a recurrent mass in the same location that was removed via hemimandibulectomy. The mass was diagnosed as a parosteal osteogenic sarcoma.