In this study, we report a tumor that resembled previously reported uncommon tumors histologically similar to ameloblastoma or adenomatoid odontogenic tumor (AOT), showing the formation of hard tissue. We evaluated the histological characteristics by reviewing the literature. The patient was a 19-year old male. The lesion was located from the canine to third molar in the right mandible and was unicystic with a comparatively clear demarcation. The tumor tissue was cystic overall, showing multiple formation of small and large cysts. The tumor tissue resembled a variant form of plexiform ameloblastoma. Formation of dentin and dentinoid was observed in the tumor stroma, whereas formation of enamel was not observed. Very few cases of a variant form of ameloblastoma that shows formation of dentinoid have been reported, and the histological picture in this study closely resembled previously reported "adenoid ameloblastoma with dentinoid".