ABSTRACT: The desmoplastic ameloblastoma (DA) is a rare variant of the conventional ameloblastoma. It accounts for only 4% to 13% of all ameloblastomas. In this article, we describe the case of a young child affected by a giant neglected DA of the jaw. Preoperative biopsy demonstrated the extremely rare osteoplastic variant of DA. The patient was submitted to segmental mandibulectomy and immediate reconstruction with a free fibula osseous flap. The postoperative period was uneventful. The patient was very satisfied with the functional and aesthetic results of the procedure. In case of such rare variants of ameloblastoma, it is mandatory to preoperatively recognize them to allow the adequate treatment modality to be provided.