Giant peripheral ossifying fibroma with coincidental squamous cell carcinoma: a case report.

Background: Peripheral ossifying fibroma is an inflammatory or reactive hyperplasia of the gingiva that is usually small. It is formed by hard tissue in fibrous tissue, and the name "neoplastic lesion" has tended to be used frequently in Europe and America. Clinically, peripheral ossifying fibromas are painless, solitary, exophytic, sessile, or pedunculated and more frequently found in females than in males. To the best of our knowledge, there have been no reports of malignant cases. We herein report the case of giant peripheral ossifying fibroma with squamous cell carcinoma.

Case Presentation: The patient was an 83-year-old Japanese woman who visited our hospital with a gingival massive mass. She was referred to us for an examination and treatment because it was difficult to perform tracheal intubation for surgery of sigmoid colon cancer at another hospital. The mass measured 83 × 58 × 35 mm, and it protruded to the extra-oral region from the right maxillary premolar alveolar region. Panoramic X-ray revealed the shadow of the mass in the right maxillary premolar region, which included some hard tissue. Computed tomography showed scattering calcified images in the mass. Magnetic resonance imaging was not performed because she had vertebral artery clips and screws in her forehead. Given the above findings, we performed a biopsy under local anesthesia. However, we were unable to diagnose absolutely whether the dysplastic squamous epithelia were pseudocarcinomatous hyperplasia of the gingiva or well-differentiated squamous cell carcinoma. Therefore, tumor resection was performed under general anesthesia. The histopathological diagnosis was peripheral ossifying fibroma with coincidental squamous cell carcinoma. There have been no signs of recurrence during follow-up as of 2 years after surgery.

Conclusions: The etiology of giant peripheral ossifying fibroma with squamous cell carcinoma is still not definite. Therefore, careful observation is necessary. It needs to be examined by accumulation of more cases in the future. We herein report the case of giant peripheral ossifying fibroma coincidental squamous cell carcinoma.