Fig. 1

Clinical and histological appearance of Case 1. a A tumor mass on the left side of the posterior dorsum of the patient’s tongue, covered by healthy looking oral mucosa. b On histological examination, a nodule of matured bone surrounded by fibrous stroma and lined with stratified squamous epithelium was noted. c Higher magnification of the tumor showing matured bone with lamella structures surrounded by fibrous connective tissue. Although no identical osteoblastic or osteoclastic reactions are observed, osteocytes can be seen within the lacunae