Cemento-ossifying fibroma (COF) is classified as a fibro-osseous lesion and usually presents as a progressively growing lesion that can reach a large size if left untreated. Fibrous dysplasia (FD) is a non-neoplastic development that affects the craniofacial bones and is characterized by painless hypertrophy due to the replacement of bone by abnormal fibrous tissue. Herein, a case of concurrent occurrence of COF and FD involving the right mandible is described in a 14-year-old male patient. In this review, the current knowledge of FD and COF is summarized, emphasizing the importance of integrating the understanding of clinical, radiographic, and histopathological features. In addition, the relevant aspects associated with differential diagnosis and patient care are evaluated.

A 31 years old female had been suffered from a bony swelling in right premolar region of the mandible for 12 years, recently grown rapidly. A fistula tract developed on the right anterior mandibular border, but the lesion was relatively asymptomatic. In the radiological examination, the tumor mass was irregularly mixed with radiolucent and radiopaque areas, forming multiple cystic spaces. Under the diagnosis of calcifying odontogenic cyst, the mandibular mass was resected and examined pathologically. After decalcification, the dissected tumor mass showed multiple small cystic spaces and calcifying fibrous tissue, mimicking calcifying odontogenic cyst or ameloblastoma. Histological observation showed many calcifying cementoid materials and ossifying trabeculae. The cystic spaces were turned out to be dilated vascular channels lined by endothelial cells, containing plasma fluid. However, the main lesion was diagnosed as cemento-ossifying fibroma (COF), and the atypical vascular channels were greatly dilated and gradually expanded the whole tumor mass. The present COF was examined through immunohistochemical (IHC) array, and investigated for tumor cell characteristics, exhibiting abnormal ossification and aneurysmal cystic changes. IHC array disclosed that the tumor cells grew progressively in the lack of apoptosis, and that they showed lower expression of RUNX2 than BMP-2, RANKL, and OPG, and increases of protein expression in HIF-1α, VEGF-A, and CMG2. These data suggested that the reduced expression of RUNX2, osteoblast differentiation factor, be relevant to abnormal ossification of COF, and that the consistent expressions of angiogenesis factors be relevant to de novo angiogenesis in COF, subsequently resulted in aneurysmal cystic changes.

The juvenile ossifying fibroma, differentiated from the large group of ossifying fibroma based on the patient’s age, common sites, and clinical characteristics, is a rare but locally aggressive benign tumor with high recurrence rate. Herein, we report a case of juvenile ossifying fibroma located in the right mandible, which is an uncommon site. A 8-years- old male child presented to the pediatric unit of our institution with swelling on the right mandible. Radiographically, it was presented as an expanded and radiolucent lesion. Histology revelaed hypercellular fibroblastic proliferation with anastomosing osteoid trabeculae with rounded, strongly basophilic calcified mass rimmed by osteoblasts. Surgical management was done, and regular follow-up is advised

The ossifying fibroma (OF), with the microscopic features of trabuclae or spherules of bone or cementum-like material in a cellular fibrous connective tissue stroma, is one of the most common benign fibro-osseous lesions in the jaw bones. The OF often occurs in patients from 20 to 40 years of age, which is a definite female predilection. The mandibles are involved far more often than the maxillas, especially the pre-molar and molar regions. It is slow-growing, bone producing, asymptomatic and well-demarcated. The OF is a disorder of odontogenesis or osteogenesis ascribed to bone marrow stroma cells (BMSCs) abnormality. However, the detailed mechanisms of OF’s oncogenesis, cytodifferentiation, and tumor progression remain unknown. In this article, we reported a huge central OF on the anterior mandible. The lesion was enucleated and peripheral ostectomy was done via intraoral approach and reconstructed with vascularized iliac block bone graft. After 25 months of follow up, the tumor had not recurred. This case shows that OF may be successfully treated by conservative surgical enucleation and peripheral ostectomy.