December 2015 Residency Program Case of the Month | Department of Pathology UC Davis Health System

Answer:

B)  Cemento - ossifying fibroma

Introduction:

Cemento- Ossifying Fibroma (COF) is a benign fibro-osseous-tumor that the World Health Organization (WHO) classifies as a fibro-osseous neoplasm. These lesions can arise from any part of the craniofacial skeleton, although the majority of the cases occur in the maxilla and mandible.

Cemento-Ossifying Fibroma present as slow growing, expansile, and rarely multifocal bony lesions. They have a female predominance and usually present in the third and fourth decade. They are relatively painless and thus asymptomatic until progression leads to facial asymmetry or mass effect on adjacent structures.

Imaging is helpful in establishing the diagnosis as well as for surgical planning. Computed tomography characteristics of Cemento-Ossifying Fibroma include a well circumscribed, lucent, target lesion with root divergence.

Primary treatment is complete surgical resection with reconstruction to restore the aesthetic appearance and function of the craniofacial skeleton.  Approaches for resection are varied and depend on the location and the extent of disease. Radiotherapy is usually contraindicated, especially in the pediatric population, due to the risk of malignant transformation.

Discussion:

The WHO classifies COF as a fibro-osseous neoplasm included among the non-odontogenic tumors derived from the mesenchymal blast cells of the periodontal ligament with a potential to form fibrous tissue, cement, bone, or a combination of these elements that predominantly arise in the maxilla and mandible. However, there is a controversy over such an origin, since tumors of similar histology have been reported in bone lacking periodontal ligament and such as ethmoid, frontal or even long bones of the body.

The characteristic histopathology of COF demonstrates the presence of generally hypercellular fibrous tissue with the occasional presence of islands of bone tissue or cementiform calcifications. Within the fibrous stroma we observe mineralized tissue masses of basophilic appearance, corresponding to osteoid material or cement, distributed throughout the lesion to one degree or other, and accompanied by dystrophic calcifications with darker or basophilic staining characteristics. The morphology is benign, with very little proliferative activity and the absence of atypias or necrosis.

Work up includes a CT scan to assist with diagnosis and surgical planning. Complete excision of a COF lesion is the treatment of choice. The surgical approach is dictated by anatomic location and tumor size. Pre-operative computer modeling can aid with reconstruction. Surveillance imaging can be used to monitor for recurrence.

References:

1. Ram R, Singhal A, Singhal P. Cemento-Ossifying Fibroma. Contemp Clin Dent. 2012 Jan-Mar; 3(1): 83–85
2. Carvalho B, Pontes, M, Garcia H, Linhares P, Vaz R. Ossifying Fibroma of the Craniofacial Skeleton. Histopathology – Reviews and Recent Advances. 2012. Chapter 7: 121-132.
3. Nakagawa, K., Y. Takasato, et al. (1995). "Ossifying fibroma involving the paranasal sinuses,orbit, and anterior cranial fossa: case report." Neurosurgery 36(6): 1192-1195.
4. Silvestre-Rangil J, Javier Silvestre F, Requeni-Bernal J, Cemento-ossifying fibroma of the mandible: Presentation of a case and review of the literature. J Clin Exp Dent. 2011;3(1):e66-9.

Collaborators:

Christopher Le, M.D.
Kiarash Shahlaie, M.D.
E. Bradley Strong, M.D., FACS