Introduction: Intraosseous mucoepidermoid carcioma of the jaw is cosidered as a rare primary central tumor wich rarely occurs within children.

Methods: A 12-year-old girl, referred to the dentistry school of Yazd, participated in this study, who complained of swelling in right posterior region of maxilla. She did not have any pain, paraesthesia, and tenderness. Moreover, cervical lymphadenopathy was absent. Intraoral examinations revealed buccal and palatal expansion without ulcer and in color of mucosa, which extended from 14 to 18 region in the right side of the maxilla and palatal tilt in theeth 14, 15, 16. On radiographic examination, CT scan showed destruction of medial wall and inferior border of maxillary sinus, hard palate and buccal cortical plate. Histopathological features confirmed mucoepidermoid carcinoma. Right partial hemimaxillectomy was performed as the treatment option.

Discussion: Pathogenesis of these tumors is still unrecognized. Neoplastic transformation of the epithelial lining of maxillary sinus or minor salivary gland can cause intraosseous mucoepidermoid carcinoma.

Conclusion: As the study findings revealed, due to invasive process of these tumors specifically in maxilla, early diagnosis and radical resection play an important role in regard with eradication of this tumor as well as improvement of such patients, and their survival rate.