Many breakthroughs have been made in the past decade regarding our knowledge of the biological basis of the diffuse gliomas, the most common primary central nervous system (CNS) tumors. These tumors as a group are aggressive, associated with high mortality, and have a predilection for adults. However, a subset of CNS glial and glioneuronal tumors are characterized by a more circumscribed pattern of growth and occur more commonly in children and young adults. They tend to be indolent, but our understanding of anaplastic changes in these tumors continues to improve as diagnostic classifications evolve in the era of molecular pathology and more integrated and easily accessible clinical databases. The presence of anaplasia in pleomorphic xanthoastrocytomas and gangliogliomas is assigned a WHO grade III under the current classification, while the significance of anaplasia in pilocytic astrocytomas remains controversial. Recent data highlight the association of the latter with aggressive clinical behavior, as well as the presence of molecular genetic features of both pilocytic and diffuse gliomas, with the recognition that the precise terminology remains to be defined. We review the current concepts and advances regarding histopathology and molecular understanding of pilocytic astrocytomas, pleomorphic xanthoastrocytomas, and gangliogliomas, with a focus on their anaplastic counterparts.
Bibliographical noteFunding Information:
This work was supported in part by the Pilocytic/Pilomyxoid Fund, including Lauren’s First and Goal, and the Stick it to Brain Tumors Annual Women’s Ice Hockey Tournament (F.J.R.); Department of Defense Grant W81XWH-18-1-0496 (FJR); NIGMS Medical Scientist Training Program Award T32-GM007309 (E.P.), and NIH Grant P30 CA006973 to the Sidney Kimmel Comprehensive Cancer Center (PI: W. Nelson).
© 2019, The Japan Society of Brain Tumor Pathology.
- Pilocytic astrocytoma
- Pleomorphic xanthoastrocytoma