A case of a relatively large peripheral ameloblastoma

We describe a 73-year-old man with a relatively large peripheral ameloblastoma arising from the anterior part of the mandibular gingiva. Clinical examination of the lesion showed a globular mass, about 40×30mm in diameter, which was elastic hard and had a wide base that closely adhered to the alveolar bone. The base partially extended to the floor of the mouth, and the remaining teeth (5-4) adjoining the mass were quite loose. An Xray film disclosed a wide area of superficial resorption in the alveolar bone surrounding the remaining teeth. A biopsy was performed, and the histological diagnosis was ameloblastoma. Based upon the diagnosis of peripheral ameloblastoma, excision of the tumor tissue was performed with the patient under general anesthesia. Pathological examination of the specimen revealed neoplastic ameloblastic cells proliferating chiefly in the submucosa. The neoplastic cells were directly contiguous with the surface squamous epithelium. Individual tumor nests consisted of peripheral layers of columnar or cuboidal cells and enclosed central areas of reticular or partially keratinized acanthomatous cells. Discrete islands and nests of tumor cells were set in a loose collagenous stroma with hyalinization. As of 4 years after the operation, no sign of recurrence has been observed.