Ameloblastoma with adenoid features with multiple local recurrences: report of a case with clinicopathologic and immunohistochemical studies

Ameloblastoma with adenoid features is characterized by the formation of cribriform or glandular tubular structures in addition to the conventional ameloblastoma; however, many aspects of the clinical and histologic characteristics are unclear. We report a case of ameloblastoma with adenoid features that occurred in the mandible and had multiple recurrences. The patient was a 54-year-old woman who presented with a chief complaint of painless swelling in the left mandibular molar region. On the first visit, a bone expansion was noted in the lingual alveolar region of the left mandibular molar. Panoramic radiograph and computed tomography revealed a unilocular radiolucent finding extending from the left mandibular first molar to the anterior edge of the left mandibular ramus. A biopsy was performed and the diagnosis was ameloblastoma. Therefore, we performed left mandibular tumor resection. Histopathologic findings showed that tissue corresponding to the conventional ameloblastoma had proliferated, and the tumor nests had a duct-like and cribriform structure. However, no whorl/morula-like structure or dentinoid was observed, leading to a diagnosis of ameloblastoma with adenoid features. Thereafter, the tumor recurred twice, and resection surgery was performed, but both cases showed the same histopathologic findings as the initial surgery. Morphologic features are important to distinguish between ameloblastoma with adenoid features and conventional ameloblastoma. In addition, ameloblastoma with adenoid features has a stronger tendency to recur than conventional ameloblastoma, and surgical resection with a sufficient margin of safety and strict postoperative follow-up are necessary.