Classifications of childhood brain tumors.

Diagnostic classifications of brain tumors do not necessarily reflect natural orders in biology. They are hypothetic statements about relationships among histologic features within tumors that have been fabricated for the purposes of understanding, communicating, and predicting brain tumor biology. Historically, they have been constructed in response to specific needs and have changed to meet new needs. The classifications in use today are built on arbitrary a priori dicta and assumptions that may not stand scientific scrutiny and may obscure efforts of physicians at prognosis. Classifications ignore the influence of site and age upon prognosis. For future use, the differing goals of prognosis and genesis may require different classifications.