Primary intraosseous myoepithelioma of the mandible with ameloblastomalike features.

Primary intraosseous salivary gland tumors of the jaw are overwhelmingly malignant. We describe, for the first time, a genuine myoepithelioma originating centrally in the mandible. A 33-year-old man had a well-circumscribed, unilocular osteolytic lesion between the roots of the mandibular second premolar and first molar with no extraosseous extension. Histologically, an encapsulated, solid/trabecular tumor was composed of benign epithelioid > spindled > basaloid > plasmacytoid cells and showed a distinctive myoepithelial immunoprofile. Multiple sections revealed neither duct formation nor myxochondroid stroma. In addition, focal areas shared features with conventional ameloblastoma histologically and immunohistochemically. This unique biphenotypic cellular and architectural make-up indicates the possibility of divergent myoepithelial and ameloblastic differentiation in the present jawbone tumor.