Myofibroblastoma of the tongue: A case report with immunohistochemical findings

Myofibroblastoma is a rare benign stromal neoplasm with myofibroblastic differentiation most often seen in the breast. In the oral region, only one case of myofibroblastoma has been reported so far; therefore, the diagnostic criteria of this tumor are still controversial in the field of oral pathology. Herein, the authors present a case of myofibroblastoma of the tongue and demonstrate the usefulness of immunohistochemistry in diagnosing this tumor. Histologically, the tumor was composed of interlacing bundles of spindle-shaped or oval cells with hyalinized stroma and amianthoid fibers. Immunohistochemically, the tumor cells showed characteristic features of mammary type myofibroblastoma: diffuse immunoreactivity for desmin, vimentin, and Bcl-2; focal immunoreactivity for α-smooth muscle actin, CD34, and cyclin D1; and no immunoreactivity for h-caldesmon. The pathological diagnosis of myofibroblastoma was made. The authors propose myofibroblastoma as a distinctive entity in the oral region, which should not be confused with other spindle-cell tumors or hamartomatous proliferation with myofibroblastic differentiation, and recommend the inclusion of extramammary myofibroblastoma in the differential diagnosis of soft tissue tumors of the oral cavity.