A case of calcifying epithelial odontogenic tumor with malignant transformation after two recurrences. Issue 3 (May 2021) - Aoki, Kazumitsu
Abstract: A calcifying epithelial odontogenic tumor (CEOT) is a relatively rare benign odontogenic tumor, which was described by Pindborg in 1955. Although benign, CEOT are locally infiltrative tumors with a tendency to invade adjacent bone. We report a case of calcifying epithelial odontogenic tumor with malignant transformation after two recurrences. The patient was a 78-year-old man. He had swelling of the mandibular anterior, and he was referred to our department in July 2015. The panoramic X-ray film showed a radiolucent image in the anterior mandible, and found a lesion-like calcification inside. In November 2015, the patient underwent tumorectomy of the mandible under general anesthesia. The histopathological diagnosis was CEOT. After the first surgery, the tumor recurred twice within 2 years and 5 months. In April 2018, we found swelling of the excised lingual gingiva, and an MRI scan showed a mass-like lesion. Diagnosis of recurrence, we performed marginal mandibulectomy in May 2018. Recurrent tumors had malignant features, such as increased nuclear pleomorphism with frequent mitotic figures, as well as increased proliferative activity assessed by immunostaining for Ki-67. Histopathological examination diagnosed transformation to malignancy. There have been no signs of recurrence or metastasis during follow-up as of 2 years and 3 months after re-operation.