Fibrous dysplasia is the dysplasia of osteogenic mesenchymal tissues, of which the lesion development often stops after pubertal growth in many cases. In the present case, fibrous dysplasia of the mandible was suspected at the first consultation when the patient was 14 years old. After long-term follow-up, a propensity of mild buccolingual lesion enlargement and pain in the wisdom tooth inside the lesion area were found and thus tooth extraction was performed. Subsequently, the enlargement of a cyst-like area was observed within the lesion. Since the imaging findings indicated some changes in the internal characteristics, re-enlargement of the lesion and its malignant transformation could not be ruled out, thus requiring careful follow-up.
