We report a case of osseous dysplasia associated with a radiolucent cyst-like bone cavity in the molar region of the mandible. A 46-year-old Japanese woman visited our hospital because of a pain on the right side of the mandible. A bone biopsy of the lesion revealed osseous dysplasia. The cyst-like bone cavity lesion contained serous content. Branches of inferior alveolar nerve were observed, whereas no epithelial structure was found on the wall of the cavity. The radiopaque lesion was solid and contained fibrous bone, therefor we did not consider surgical intervention of this lesion. However, we considered surgical treatment for the cyst-like lesion by filling the bone cavity with platelet-rich plasma to stimulate bone healing. We concomitantly performed an apicoectomy for the involved teeth in the bone cavity. After a long-term follow-up (10 years), ossification was observed in the bone cavity in the molar region with no signs of recurrence, and the osseous dysplasia lesion in the premolar region was stable without showing signs of growth.
