Internal morphology of ameloblastomas: a study of 24 resected specimens

The objectives of this study were to describe the internal macroscopic architecture of resected specimens of ameloblastoma and to correlate the findings with radiographs and microscopic features.

Resection specimens of 24 ameloblastomas were retrieved from the files of the Department of Oral Pathology at the University of Limpopo. The neoplasms were sectioned in parallel slices and the macroscopic features recorded and each slice was radiographed and sampled for microscopic examination. The macroscopic features were correlated with respective microscopic and radiological appearances.

Twenty-three ameloblastomas affected the mandible and 1 the maxilla and measured between 3.3 and 20 cm in greatest diameter. Six cases were unicystic, 2 of which showed incomplete septae both of which presented multilocular on radiographs. Intracystic proliferations were present in 15 cases. These proliferations showed macroscopic features of either small or large nodules with or without the formation of confluent plaques, focal papillary lesions, or multinodular masses that protruded into the cystic cavities. Microscopically these proliferations were characterized by foci of inflammation or plexiform or solid epithelial proliferations, one of which showed a focus of carcinoma in situ, adenomatoid differentiation and another osteodentin deposits. Seven cases had foci of stromal desmoplastic change, one of which exhibited mineralized deposits resembling bone.

The assessment of the cystic nature of ameloblastomas on 2-dimensional radiographs is inaccurate. Intraluminal proliferations, in situ carcinomatous change, adenoid differentiation, stromal osteodentin, and bone deposits and desmoplasia were found to be focal rather than generalized phenomena in resection specimen of ameloblastoma.