Grading of the tumors of the central nervous system

The first edition of the International Classification of Diseases (ICD) dates back to 1893.

The current review (ICD-10) dates back to 1994, came into use in the U.S. in 2015, and is revised yearly, being very comprehensive.

In this last edition, the Arabic numeral after the character "/" indicates the "behavior" of the neoplasia, with the following meaning:[3]

A brain tumor composed of benign cells, but located in a vital area (as the brain is), can be considered to be life-threatening — although the tumor and its cells would not be classified as malignant.

The St. Anne-Mayo grade has four categories of tumors:[citation needed] The World Health Organization (WHO) grading system[5][10][11][12] is contained in the volume Histological Typing of Tumours of the Central Nervous System, whose first edition dates back to 1979 (now up to the 5th edition, published online in 2021).

MRI of a diffuse astrocytoma with differing degrees of differentiation.
Macroscopic pathology of glioblastoma .
MRI of a patient with anaplastic astrocytoma .
Pilocytic astrocytoma . Nuclear hyperchromasia and pleomorphism are common. Note the typical cellular elongation, and, at the center of the illustration, the eosinophilic granular body that populates pilocytic astrocytomas and certain other slowly growing gliomas .