Clinicopathological Diagnosis of Gliomatosis Cerebri

Regarding the definition of gliomatosis cerebri (hereinafter referred to as "GC"), the 3rd edition of the WHO Classification of Central Nervous System Tumors (hereinafter referred to as "3rd ed.") provides only a five-line description that GC is a diffuse, frequently bilateral, glioma that infiltrates the brain, involving more than two lobes. It often extends to the infratentorial structures and even to the spinal cord. Compared with this, the definition in its 4th edition (hereinafter referred to as "4th ed.") is described in 13 lines, stating that GC involves at least 3 lobes and is usually bilateral, extending from the cerebral white matter, including the deep and subcortical portions, and often infiltrating the brain stem and the spinal cord. In the 4th ed., GC is characterized by a widespread infiltration of the brain by tumor, occurring as bilateral lesions involving commissural fibers, and frequently infiltrating from the brain stem to the spinal cord. Moreover, the 4th ed. states that GC is mainly astrocytic tumor but, in some cases, mainly consists of oligodendroglial tumor cells (Akimoto, 2004; Balko, 1996; Levin, 2004; Sanson, 2004, Taillibert, 2006). Unlike the 3rd ed., which specifies the histological malignancy as Grade III, the 4th ed. rates it basically as Grade III, without specifying it, although recognizing the importance of the evaluation of histological malignancy, in consideration of the possibility that the grade may be underestimated in some cases due to tissue sampling problems (Akimoto, 2004; Nishioka, 1996). These changes in the description of the definition in the WHO Classification have reflected the findings of many clinicopathological researches on GC. This situation requires us neuro-oncologists to diagnose GC before operation and to provide appropriate treatment. In that sense, it is important to evaluate the extent of tumor progression by imaging diagnosis, mainly using MRI, and to perform adequate tissue sampling to enable accurate histopathological diagnosis, in accordance with the 4th ed. (Akimoto et al., 2004). In addition, it is important to establish a treatment protocol mainly consisting of adjunctive therapy.