FROM THE ARCHIVES OF THE AFIP - GLIOBLASTOMA-MULTIFORME - RADIOLOGIC-PATHOLOGICAL CORRELATION

Astrocytic tumors are divided into two basic categories: circumscribed (grade I) or diffuse (grades II-IV). All diffuse astrocytomas tend to progress to grade IV astrocytoma, which is synonymous with glioblasto ma multiforme (GBM). GBMs are characterized by marked neovascularity, increased mitosis, greater degree of cellularity and nuclear pleomorph ism, and microscopic evidence of necrosis. Several genetic abnormaliti es have been associated with the development of GBM: Ln some cases, th e abnormality is inherited (eg, Li-Fraumeni syndrome); in others, gene tic alteration appears to result from mutation into an oncogene or det erioration of the tumor-suppressor gene p53. A common, distinctive his topathologic feature of GBM is pseudopalisading. The most common imagi ng appearance of GBM is a large heterogeneous mass in the supratentori al white matter that exerts considerable mass effect. Less frequently, GBM can occur near the dura mater or in the corpus callosum, posterio r fossa, and spinal cord. GBM typically contains central areas of necr osis, has thick irregular walls, and is surrounded by extensive, vasog enic edema, but the tumor may also have thin round walls, scant edema, or a cystic appearance with a mural nodule. GBMs most commonly metast asize from their original location by direct extension along white mat ter tracts; however, cerebrospinal fluid, subependymal, and hematogeno us spread also can occur. Given the rapidly growing body of knowledge about GBM, the radiologist's role is more important than ever in accur ate and timely diagnosis.