Intramuscular (infiltrating) lipoma of the tongue.

A patient with an intramuscular lipoma (infiltrating lipoma) located within the tongue is presented. There is only one previously reported case of an intramuscular lipoma located within the oral cavity. Because of its infiltrating nature, this tumor may be mistaken for a liposarcoma. Here, as in other sites, the important characteristics serving to distinguish an infiltrating lipoma from a liposarcoma are the absence of lipoblastic proliferation, myxoid differentiation, cellular pleomorphism, increased vascularity, and mitotic activity. Achievement of adequate surgical margins is essential, as the recurrence rate may be as high as 62.5% without complete excision.