[Ultrastructural analysis of liposarcoma]

9 cases of liposarcoma, including 5 myxoid type, 3 pleomorphic type and 1 well differentiated type, were studied with light, electron microscopy and immunohistochemistry. Comparative observations revealed similarities between liposarcoma cells and cells of developing fat tissue. Liposarcoma cells resemble primary mesenchymal cells, fibroblasts, early, midstage and late lipoblasts or mature lipocytes. But certain differences also exist: First, atypia in liposarcoma cells, such as the appearance of mono- or multinuclei giant lipoblasts in some cases. Second, certain types of liposarcoma are predominated by lipoblasts of a specific stage. Under electron microscope, transitional morphology from both primary mesenchymal cell and fibroblast to lipoblast can be observed, which is an indication that lipoblasts may originate from these two types of cells. Differential diagnosis by electron microscopy is also discussed.