Bilateral Fibro-Osteoma of the Maxilla in a Monkey

Abstract

A report was given of 2 unusual, bilateral symmetrical os-teodystrophies of the maxilla in a monkey. Roentgeno-graphic examination of these maxillary protuberances reveals 2 large bilateral, hazily-diffuse, non-erosive areas, devoid of cortical margins. These growths expand anteriorly and inferiorly. Grossly, the mucous membrane is intact and unchanged except for marked thickening. On sectioning, the contents of the bony tumor appear dirty-gray, coarse, granular and cut readily with the dental burr. Microscopic examination of the overlying mucous membrane indicates an intact, somewhat squat but essentially normal epithelium. The sub-epithelium is densely fibrous with sparse nuclei and occasional blood vessels. There are narrow, regular bony trabeculae throughout this outer fibrous tissue. The central portions of these trabeculae are still calcified and deeply staining. They are encircled by layers of osteoid tissue of varying thickness, in a fashion similar to that seen in osteo-malacia. In contrast, a specimen from further within the lesion is typical of the many small eosinophilic trabeculae of a fibro-osteoma. The marrow spaces have been replaced by dense, non-inflamed connective tissue. There is little evidence of lacunar resorption. Few osteoclasts are present. A tentative histopathological diagnosis of bilateral fibro-osteoma, with a peripheral osteomalacia, is suggested.