Cementoblastoma and Focal Osseous Dysplasia: differential morphological aspects of tumoral and dysplastic “cemento-osseous” trabeculae

Introduction: The wide variety of pathologies comprised in the group of benign fibro-osseous lesions of the jaw bones includes cementoblastoma and focal osseous dysplasia. Both lesions have similar clinico-radiographic and histopathological features, and pose a challenge to differential diagnosis, even more so when focal osseous dysplasia is associated with a tooth. Objective: To evaluate and define the morphological aspects that differentiate tumoral “cemento-osseous” trabeculae that form in cementoblastoma from dysplastic “cemento-osseous” trabeculae seen in focal osseous dysplasia. Materials and methods: Twenty-two cases of cementoblastoma and 94 cases of focal osseous dysplasia were retrieved from the archives of the Oral Pathology Department, School of Dentistry, University of Buenos Aires (1960-2015). The histopathological features were analyzed and the relation of the lesion to the involved tooth was evaluated in 6 cases of cementoblastoma and in 24 cases of focal osseous dysplasia. Results: Although both pathologies showed formation of sclerotic “cemento-osseous” trabeculae with a pagetoid appearance, trabeculae observed in cementoblastoma showed marked cellularity with numerous cementocytes and marked cementoblastic-cementoclastic activity (72%), and a sun ray appearance at the periphery; 15% of cases showed necrosis and inflammatory infiltrate. The trabeculae formed in focal osseous dysplasia were paucicellular with reduced cemento-osseo blastic and clastic activity (32%), and showed total necrosis in 80% of cases and inflammatory infiltrate in 27% of cases. All cases of cementoblastoma examined to analyze the relation of the lesion to the involved tooth showed root destruction, whereas the studied cases of focal osseous dysplasia exhibited trabecular apposition on the root surface and continuity with the lesion. Conclusions: The morphological findings observed here and their relation with the involved tooth, to our knowledge not reported previously, would allow establishing differential diagnosis between tumoral and dysplastic “cemento-osseous” trabeculae and defining both entities.