Background. The occurrence of osteoid-chondral elements in gliosarcoma is extremely rare and has been reported in only two cases. A new, rare case of gliosarcoma with osteosarcomatous differentiation in a 55-year-old man and histogenesis of osteoid-chondral tissue in gliosarcoma is discussed.
Methods. Surgically removed tumor tissues were examined immunohistochemically and electron microscopically, and a histologic examination was performed.
Results. Immunohistochemical and electron microscopic studies confirmed the presence of glial, fibroblastic, and osteoid-chondral elements. A major part of the sarcomatous tissue was undifferentiated and stained only by vimentin. Some areas of osteoid-chondral tissue were positive for glial fibrillary acidic protein (GFAP).
Conclusions. These data suggest that osteoid-chondral elements came from the sarcomatous portion and GFAP positivity is not restricted to astrocytes and has been seen particularly in chondroid areas of non-glial tumors.