Sclerosing odontogenic carcinoma with fibro-osseous components and delayed multiple spinal metastasis: A case report

Sclerosing odontogenic carcinoma (SOC) is a very rare tumor that was newly listed in the 2017 World Health Organization (WHO) classification of head and neck tumors. The latest WHO classification includes the lack of metastatic potential and hard tissue formation to the “Definition” and “Histopathology.” Although SOC has been believed a low-grade odontogenic carcinoma, two previous studies describing SOC’s metastatic potential have been published in English. We herein show a case of SOC with both fibro-osseous components and distal metastasis. The patient was a 55-year-old Japanese male whose right mandible had a mass that had been causing him discomfort for a long period. Radiographic features showed a diffuse and borderless lesion in the right mandible. Based on a preoperative local biopsy, fibrous dysplasia was diagnosed. A surgical specimen from the subsequent excision revealed odontogenic carcinoma with fibro-osseous components. A final diagnosis of SOC was made 2 months after the first excision, after an additional segmental resection of mandible was examined. Unexpectedly, multiple spinal metastases occurred 7 years after surgery, and these metastases were excellently cured by radiation therapy. Herein, we outline the case details and tips for the accurate diagnosis and treatment of SOC based on the presentation of its uncommon histological pattern.