Primary myxoid liposarcoma with rhabdomyoblastic differentiation.

We report a unique case of primary myxoid liposarcoma of the floor of the mouth, in which well-differentiated rhabdomyoblasts were present. The tumor was incompletely excised. The patient is free of recurrence or metastasis following a course of radiotherapy. Heterologous components found in a liposarcoma include leiomyosarcoma, rhabdomyosarcoma, chondrosarcoma, osteosarcoma, and angiosarcoma. These elements have been described mainly in dedifferentiated liposarcomas situated in the retroperitoneum. To our knowledge, there has been only one report of a liposarcoma with rhabdomyosarcomatous differentiation occurring in the absence of a dedifferentiated component. The clinical implications of the presence of heterologous components without dedifferentiation are unclear.