Gliosarcoma with liposarcomatous component, bone infiltration and extracranial growth.

Gliosarcoma is a highly malignant brain tumor consisting of both a glioblastoma and a mesenchymal component. The latter typically resembles fibrosarcoma, but differentiation patterns resembling osteosarcoma, chondrosarcoma, angiosarcoma and rhabdomyosarcoma have also been described. Molecular-genetic studies have shown that both glioblastoma and the mesenchymal component share identical cytogenetic abnormalities or mutations, suggesting a monoclonal origin from glial cells. We report an unusual case of gliosarcoma that presented as a large intracerebral tumor with infiltration of the temporal bone and the soft tissues in the infratemporal fossa. Microscopically, the tumor consisted of alternating areas of glioblastoma and fibrosarcoma. Focally, areas ofosteosarcomatous and liposarcomatous differentiation were found. Although gliosarcoma with transcranial penetration is very rare, it should be suspected in case of intracranial tumor with glioblastoma-imaging features, infiltration of bone and extracranial growth. Our case of liposarcomatous differentiation in gliosarcoma--together with another very recently reported similar case--expands the morphologic heterogeneity of this peculiar brain tumor.