A case of ameloblastic fibroma in an infant

A case of ameloblastic fibroma which is very rare in comparison with ameloblastoma in occurrence was reported.The patient was a 5 year-old female who visited our hospital because it was noticed during dental inspection that she had an abnormal radiolucent lesion in the right molar region of the mandible. There was slight and diffuse swelling in the right mandibular region extraorally, and a bony expansion in the right molar region intraorally. X-ray examination showed a multilocular radiolucent shadow in the region from C apex to 6 tooth germ. The clinical diagnosis was ameloblastoma. Enucleation was done under general anesthesia. The tumor was a white solid mass with a thick fibrous capsule, and was about 3.0cm in diameter.Light microscopy showed that the tumor was composed of cellular and fibrous tissue in which there were islands and strands of odontogenic epithelium. The fine fibers were moderately stained with Azan stain and the basement membrane between the odontogenic epithelium and connective tissue was stained with both Azan and Reticulin stains. PAS-Alcian blue stain was negative. Histopathological diagnosis was ameloblastic fibroma. Under the electron microscope, tall columnar cells were observed on the periphery of the epithelial islands and strands, and were connected with each other by well developed desmosomes and gap junctions. These findings were discussed in relation to the stage of amelogenesis.There was no sign of recurrence at about a year after the operation.