Ameloblastomas are rare odontogenic epithelial tumors that occur mainly in the mandible. Despite their benign histologic appearance, they are locally aggressive with a high recurrence rate. However, a metastasizing ameloblastoma has been rarely reported. According to the current World Health Organization classification system, the definitive diagnosis of metastasizing ameloblastoma can only be carried out in retrospect, after the event of metastasis. This case report describes a patient with metastatic pulmonary ameloblastoma, 17 years after the surgical excision of an odontogenic tumor, preoperatively misdiagnosed as primary squamous cell carcinoma.