Osteosarcoma associated with cemento-osseous dysplasia: co-incidence or two related entities?

Background: Osteosarcoma of the jaws is a rare primary malignant tumor of bone. The clinical, radiological and histopathological features of a case associated with cemento-osseous dysplasia is presented.

Case report: A 57-year-old mixed-race female presented with a large, progressive, swelling of the right mandible. Radiographic examination revealed two associated lesions. Partially defined irregular radiopacities were noted in the left mandible, extending from the premolar to the molar region. The lesion had a cotton-wool appearance and resembled a fibro-osseous lesion; i.e. cemento-osseous dysplasia. A second large, expansive and irregular, radiopaque lesion was noted on the right angle of the mandible, extending beyond the inferior cortex of the mandible. The internal structure was heterogeneous and resembled irregular bone formation. The classic "sunburst" appearance of radiating bony spicules can be seen in the posterior-anterior view and the CBCT 3D reconstruction, indicating the outgrowth of the tumor matrix. Histopathological exam confirmed a final diagnosis of osteosarcoma closely associated with cemento-osseous dysplasia. The patient underwent a fludeoxyglucose-18 (FDG) positron emission tomography (PET) scan which indicated metastasis in the left lung and increased uptake in the right mandible. Chemotherapy was initially administered with a plan to resect the tumor, however, the patient demised as a result of medical complications.

Conclusion: The question in the literature remains whether these two entities are coincidentally found or arise from each other. Nevertheless, it is important for clinicians to closely monitor patients with cemento-osseous dysplasia and biopsy any suspicious lesions that may develop into osteosarcoma.