RATIONALE: Ameloblastoma is generally characterized as a benign tumor 
originating in odontogenic epithelium. However, few cases of metastatic 
malignant ameloblastoma have also been reported. Due to the low incidence of 
malignant ameloblastoma, there is no established treatment regimen. To explore 
effective treatment for malignant ameloblastoma, we reported this case study.
PATIENTS CONCERNS: This report described a case of a 28-year-old malignant 
ameloblastoma female patient with multiple metastasis (brain and lung).
DIAGNOSES: The patient presented ameloblastoma of the left mandible in 2012. 
Three years later, local recurrence and brain metastasis was observed during a 
follow-up examination. Five years later, malignant ameloblastoma was detected by 
imaging and immunohistochemistry in the bilateral multiple pulmonary nodules and 
mediastinal lymph nodes.
INTERVENTIONS: The patient was initially treated with tumor resection. Three 
years later after local recurrence and brain metastasis, she was accepted the 
extensive mandibulectomy supplemented with brain stereotactic body radiotherapy 
(SBRT). When diagnosed with pulmonary metastasis, the patient received combined 
chemotherapy regimen of MAID (mesna, adriamycin, ifosfamide and dacarbazine) for 
6 cycles.
OUTCOMES: The efficacy evaluation was partial remission (PR) after the 6 cycles 
of MAID. The last patient follow-up was July 24th 2018, and no evidence of 
progression was observed. The progression-free survival (PFS) of the patient was 
more than 9 months.
LESSONS: Surgical resection is the optimal treatment for locally recurrent 
ameloblastoma. SBRT may be an effective treatment for unresectable 
oligometastasis of malignant ameloblastoma. Finally, combined chemotherapy of 
MAID showed encouraging effects in the management of metastatic malignant 
ameloblastoma.