Here is a fleshy mass arising in the soft tissues of the lower leg. The tibia and the fibula are seen in cross section. This neoplasm proved to be a high-grade undifferentiated pleomorphic sarcoma (HGUPS), a designation replacing the prior term malignant fibrous histiocytoma. Sarcomas tend to invade locally, as can be seen here by the ill-defined margins of the mass.