Grading Of The Tumors Of The Central Nervous System
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The concept of grading of the tumors of the central nervous system, agreeing for such the regulation of the "progressiveness" of these
neoplasia A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s (from benign and localized
tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s to malignant and infiltrating tumors), dates back to 1926 and was introduced by P. Bailey and H. Cushing, in the elaboration of what turned out the first systematic classification of gliomas.
In the following, the grading systems present in the current literature are introduced. Then, through a table, the more relevant are compared.


ICD-O scale

The first edition of the
International Classification of Diseases The International Classification of Diseases (ICD) is a globally used diagnostic tool for epidemiology, health management and clinical purposes. The ICD is maintained by the World Health Organization (WHO), which is the directing and coordinating ...
(ICD) dates back to 1893. The current review (
ICD-10 ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification list by the World Health Organization (WHO). It contains codes for diseases, signs and symptoms, ...
) dates back to 1994, came into use in the U.S. in 2015, and is revised yearly, being very comprehensive.
In 1976 the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
(WHO) published the first edition of the
International Classification of Diseases for Oncology The International Classification of Diseases for Oncology (ICD-O) is a domain-specific extension of the International Statistical Classification of Diseases and Related Health Problems for tumor diseases. This classification is widely used by can ...
(ICD-O), which is now at the third edition (ICD-O-3, 2000).
In this last edition, the Arabic numeral after the character "/" indicates the "behavior" of the neoplasia, with the following meaning: * /0 benign neoplasia * /1 uncertain neoplasia (benign or malignant) * /2 neoplasia ''
in situ ''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in ...
'' * /3 primary infiltrative malignant neoplasia * /6 secondary malignant neoplasia * /9 malignant neoplasia, uncertain if primitive or secondary
For the concepts of ''benign'' and ''malignant'' neoplasia see
Tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
and
Cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
. For ''primary'' and ''secondary'' neoplasias see
Metastasis Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...
.
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.


Kernohan grading

The Kernohan grading system defines progressive malignancy of
astrocytoma Astrocytomas are a type of brain tumor. They originate in a particular kind of glial cells, star-shaped brain cells in the cerebrum called astrocytes. This type of tumor does not usually spread outside the brain and spinal cord and it does not usu ...
s as follows: * Grade 1 tumors are benign astrocytomas. * Grade 2 tumors are low-grade astrocytomas. * Grade 3 tumors are anaplastic astrocytomas. * Grade 4 tumors are glioblastomas.


St Anne-Mayo grading

The St Anne-Mayo grading system also is used to grade astrocytomas; however, this system uses four morphologic criteria to assign a grade: a) ''nuclear'' ''
atypia Atypia (from Greek, ''a'' + ''typos'', without type; a condition of being irregular or nonstandard) is a histopathologic term for a structural abnormality in a cell, i.e. it is used to describe atypical cells. Atypia can be caused by an infection ...
'',
b) ''
mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...
'',
c) ''
endothelial The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...
proliferation''-'piled-up' endothelial cells. NOT
hypervascularity Hypervascularity is an increased number or concentration of blood vessels. In Graves disease, the thyroid gland is hypervascular, which can help in differentiating the condition from thyroiditis. 90% of thyroid papillary carcinoma Papillary th ...
d) ''
necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
''.
The St. Anne-Mayo grade has four categories of tumors: * Grade 1 tumors do not meet any of the criteria. * Grade 2 tumors meet one criterion, usually nuclear atypia. * Grade 3 tumors meet two criteria, usually nuclear atypia and mitosis. * Grade 4 tumors meet three or four of the criteria.


WHO grading

The World Health Organization (WHO) grading system Centers for Disease Control and Prevention (2004).

Data collection of primary central nervous system tumors. National Program of Cancer Registries Training Materials.
'
Atlanta, Georgia: Department of Health and Human Services, Centers for Disease Control and Prevention.
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). The WHO grade has four categories of tumors: * Grade I tumors are slow-growing, nonmalignant, and associated with long-term survival. * Grade II tumors are relatively slow-growing but sometimes recur as higher grade tumors. They can be nonmalignant or malignant. * Grade III tumors are malignant and often recur as higher grade tumors. * Grade IV tumors reproduce rapidly and are very aggressive malignant tumors.
From the histological point of view the WHO system is based on the same criteria as the St Anne-Mayo system. Buckner JC, Brown PD, O'Neill BP, Meyer FB, Wetmore CJ, Uhm JH (2007).

Central nervous system tumors.
'
Mayo Clin Proc. 2007 Oct;82(10):1271-86.


Comparison of the grading systems

In the following table the various grading systems are compared (the IDC-O scale is not comprised because it is not considered a real grading system): Kleihues P, Cavenee WK, eds. (2000).
''Pathology and genetics of tumours of the nervous system. World Health Organization classification of tumours.''
Lyon, France: IARC Press .


See also

* WHO classification of the tumors of the central nervous system


References


Bibliography

* Kleihues P, Cavenee WK, eds. (2000). ''Pathology and genetics of tumours of the nervous system''.
''World Health Organization classification of tumours.'' Lyon, France: IARC Press . * Louis DN, Ohgaki H, Wiestler OD, Cavenee WK (eds) (2007). ''World Health Organization Classification of Tumours of the Central Nervous System''. IARC, Lyon {{ISBN, 92-832-2430-2.


External links


AFIP Course Syllabus
- Astrocytoma WHO Grading Lecture Handout Nervous system neoplasia