Gliomatosis cerebri: quantitative proof of vessel recruitment by cooptation instead of angiogenesis.

Gliomas are the most common primary brain tumors, many of which (especially astrocytic and oligodendroglial neoplasms) are characterized by diffuse infiltrative growth in the preexisting brain tissue. Gliomatosis cerebri is a rare glial tumor and represents an extreme example of such diffuse infiltrative growth. This growth pattern not only hampers curative treatment but also allows for vessel cooptation rather than tumor angiogenesis as a way of vessel recruitment by the tumor tissue. The goal of this study was to establish the extent to which tumor angiogenesis occurs in gliomatosis cerebri. Computerized image analysis was performed to assess quantitatively two microvascular parameters (vessel density and diameter) in different areas of a brain harboring a gliomatosis cerebri. These regions were the cerebral white and gray matter in which there was a diffuse infiltrative tumor, cerebral white and gray matter in which there was a more compact growth pattern of tumor cells, and normal cerebral white and gray matter. In addition, the authors performed immunohistochemical stainings for blood-brain barrier (BBB) characteristics (Glut-1 and PgP) on samples obtained in these different areas. The results of the quantitative analysis strongly indicated that in gliomatosis cerebri tumor, angiogenesis was completely absent, a finding that is corroborated by the fact that the microvasculature in gliomatosis cerebri persists in exhibiting immunohistochemical characteristics of the BBB. The results of this study may help resolve the difficulties in radiological detection and delineation of the diffuse infiltrative part of glial brain tumors and put the expectations for antiangiogenic treatment of such tumors into perspective.