Chondromyxoid fibroma of bone. An electron microscopic observation

A resected case of chondromyxoid fibroma of the right fibula in a 31-year-old male is presented. The histology was composed of characteristic lobular features of this tumor with abundant cartilaginous matrix. The ultrastructural study exhibited stellate, ovoid or elongated tumor cells with features of cartilage cells and abundant loose matrix with many fine filamentous structures. The nuclei were often of peculiarly indented contour and revealed thick fibrous lamina. The villous cell processes and intracytoplasmic fine filaments were prominent. No cells suggesting a fibroblast were recognized in this study. From the light microscopical and ultrastructural findings of this case, it is supported that this tumor might be derived from adult cartilage cells most likely related to the epiphyseal cartilage rather than fibroblasts.