Introduction: Adenomatoid odontogenic tumour (AOT) is a rare tumour of epithelial origin predominantly found in maxilla, and rarely found in mandible. Calcifying epithelial odontogenic tumour (CEOT) is a locally aggressive benign odontogenic neoplasm arising from epithelial tissue. This case report describes a case where the AOT mimics CEOT found in the mandible area. Case presentation: A 13-year-old female patient was referred to Persahabatan Hospital Jakarta, presented with a lump in the lower left mandible that is painless and didn't show any exudates. The lesion grew from the size of a marble to a size of a quail egg in three months. No facial asymmetry, limited mouth opening, and tooth mobilization present. Result: The surgical management of the lesion was enucleation and removal of associated impacted tooth. The prognosis for booth of them is good and recurrences are very rare after complete removal of lesion. Conclusion: The combination of the partly cystic and solid tumour of AOT/CEOT proves the complexity found among the odontogenic epithelial, however, the diagnosis can be confirmed since these tumours present with their own uniqueness in its histologic features.