Abstract
Angiomatoid fibrous histiocytoma （AFH） is a soft tissue tumor of intermediate malignancy that occurs most frequently in the extremities, but rarely occurs in the oral cavity. We report a case of the myxoid variant of AFH that occurred in the anterior mandibular region and was difficult to diagnose. The patient was a 17-year-old male. He was referred to our department with a swelling of gingiva of the right mandibular anterior teeth. An elastic soft mass of 20 mm diameter with a clear border and normal surface mucosa was found in the lingual gingiva of the right mandibular anterior teeth. No root resorption was observed on panoramic X-ray images, but resorption of the lingual cortical bone and cancellous bone between the right lower teeth was observed on CT images. MRI showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. A biopsy was performed but no definitive diagnosis was made, and it was reported to be a myxoid tumor. Tumor resection was then performed under general anesthesia, and a diagnosis of AFH was made. Two years have passed since the operation, and no recurrence or metastasis has been observed. This tumor is difficult to distinguish from other tumors based on clinical and imaging findings, and because it exhibits a variety of histopathological findings, a definitive diagnosis cannot always be obtained from a biopsy. FISH is required for a definitive diagnosis, and was used to make a definitive diagnosis in the present case.
