Myofibroblastoma of the tongue. An immunohistochemical, ultrastructural, and flow cytometric study. A case of myofibroblastoma arising in the tongue of a 77-year-old man is described. The patient presented with a submucosal tongue mass without other associated symptoms. The tumor was 2 cm in diameter, well circumscribed, and composed of uniform spindle cells arranged in fascicles. Electron microscopic examination and immunohistochemistry demonstrated a myofibroblastic origin for the tumor cells. DNA flow cytometric analysis showed a diploid DNA content of this tumor. To the authors' knowledge, this is the first report of myofibroblastoma occurring in the tongue. 