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TN 1 (05-18)

DI 24585.001 Evaluation of Tumors of the Central Nervous System (tumors of the brain and spinal cord)

A. World Health Organization (WHO) classification system for establishing the grades of tumors of the brain and spinal cord

There are several classification systems that medical sources use to identify the grades of tumors of the central nervous system (CNS). The WHO classification system is the one most commonly used in the United States when classifying tumors of the brain and spinal cord. WHO published a Fourth Edition of its classification system in 2007: WHO Classification of Tumours of the Central Nervous System.[1] WHO revised the Fourth Edition in May 2016 to account for research into molecular and genetic markers of CNS tumors: WHO Classification of Tumours of the Central Nervous System, Revised.[2] We consider a CNS tumor to be malignant if it is classified as grade II or higher in the WHO classification (see 13.00K6 and 113.00K4). (See DI 34001.034 and DI 34005.113.) CNS tumors not found in the 2007 version of the WHO classification system may instead be found in the 2016 version.

B. The grades of tumors of the CNS in the 2007 version of the WHO classification system

If the medical evidence uses a classification other than the WHO system, refer to the tables below from the 2007 version of the WHO system to help determine the tumor grade. If the tumor is WHO grade I, evaluate the tumor under the criteria in listings 11.05 and 111.05. (See DI 34001.030 and DI 34005.111.) If the tumor is WHO grade II, evaluate the tumor under listing 13.13A3 or 113.13C. If the tumor is grade III or IV in the WHO or another classification system, consider the tumor to be highly malignant and evaluate it under the criteria in listings 13.13A1 or 13.13A2 and 113.13A or 113.13B. The 2007 version of the WHO classification system is organized according to the cell type or anatomical structure of the CNS where the tumor originated.

  

Table A. WHO Grade I Tumors

Type of tumor

Name of tumor

Grade of tumor

Astrocytic tumors

Pilocytic astrocytoma[3]

I

 

Subependymal giant cell

I

Ependymal tumors

Myxopapillary ependymoma

I

 

Subependymoma

I

Choroid Plexus tumors

Choroid plexus papilloma

I

Other Neuroepithelial tumors

Angiocentric glioma

I

Neuronal and Mixed Neuronal-glial tumors

Desmoplastic infantile astrocytoma

I

 

Desmoplastic infantile ganglioglioma

I

 

Dysembryoplastic neuroepithelial tumor

I

 

Gangliocytoma

I

 

Papillary glioneuronal tumor

I

 

Paraganglioma of the spinal cord

I

 

Rosette-forming glioneuronal tumor of the fourth ventricle

I

Pineal tumors

Pineocytoma[4]

I

Schwannomas

Cellular

I

 

Melanotic

I

 

Plexiform

I

Neurofibromas

Plexiform

I

Perineurioma

Intraneural perineurioma

I

Meningiomas[5]

Angiomatous

I

 

Fibrous (fibroblastic)

I

 

Lymphoplasmacyte-rich

I

 

Meningiothelial

I

 

Metaplastic

I

 

Microcystic

I

 

Psammomatous

I

 

Secretory

I

 

Transitional (mixed)

I

Mesenchymal

Angiolipoma

I

 

Chondroma

I

 

Epitheloid haemangioendothelioma

I

 

Haemangioma

I

 

Hibernoma

I

 

Leiomyoma

I

 

Lipoma

I

 

Osteochondroma

I

 

Osteoma

I

 

Rhabdomyoma

I

 

Solitary fibrous histocytoma

I

Melanomas

Diffuse melanocytosis

I

 

Melanocytoma

I

Other Tumors related to meninges

Haemangioblastoma

I

Teratomas

Mature teratoma

I

Tumors of the Sellar Region

Adamantinomatous craniopharyngioma

I

 

Craniopharyngioma

I

 

Granular cell tumor

I

 

Papillary craniopharyngioma

I

 

Pituicytoma

I

 

Spindle cell oncocytoma of the adenohypophysis

I

   

Table B. WHO Grade II Tumors

Type of tumor

Name of tumor

Grade of tumor

Astrocytic tumors

Diffuse astrocytoma

II

 

Fibrillary astrocytoma

II

 

Gemistocytic astrocytoma

II

 

Pilomyxoid astrocytoma

II

 

Pleomorphic xanthoastrocytoma

II

 

Protoplasmic astrocytoma

II

Oligodendroglial tumors

Oligodendroglioma

II

Oligoastrocytic tumors

Oligoastrocytoma

II

Ependymomas

Cellular

II

 

Clear Cell

II

 

Papillary

II

 

Tanycytic

II

Choroid Plexus tumors

Atypical choroid plexus papilloma

II

Other Neuroepithelial tumors

Chordoid glioma of the third ventricle

II

Neuronal and Mixed Neuronal-glial tumors

Central neurocytoma

II

 

Cerebellar liponeurocytoma

II

 

Extraventricular neurocytoma

II

Meningiomas

Atypical meningioma

II

 

Chordoid meningioma

II

 

Clear cell meningioma

II

Mesenchymal Tumors

Haemangiopericytoma

II

   

Table C. WHO Grade III Tumors

Type of tumor

Name of tumor

Grade of tumor

Astrocytic Tumors

Anaplastic astrocytoma[6]

III

 

Gliomatosis cerebri

III

Oligodendroglial Tumors

Anaplastic oligoastrocytoma

III

 

Anaplastic oligodendroglioma

III

Ependymal Tumors

Anaplastic ependymoma

III

Choroid Plexus Tumors

Choroid plexus carcinoma

III

Other Neuronal and Mixed Neuronal-Glial Tumors

Anaplastic ganglioma

III

Meningiomas

Anaplastic (malignant) meningioma

III

 

Papillary meningioma

III

 

Rhabdoid meningioma

III

Mesenchymal Tumors

Anaplastic haemangiopericytoma

III

   

Table D. WHO Grade IV Tumors

Type of tumor

Name of tumor

Grade of tumor

Astrocytic Tumors

Glioblastoma

IV

Tumors of the Pineal Region

Pineoblastoma

IV

Embryonal Tumors

Atypical teratoid/rhabdoid tumor

IV

 

Central nervous system Primitive neuroectodermal tumors (PNETs)[7]

IV

 

Medulloblastoma[8]

IV

 

C. The grades of tumors of the CNS in the 2016 version of the WHO classification system

If the medical evidence uses a classification other than the WHO classification system or a tumor is not listed in the 2007 version of the WHO classification system, refer to the tables below from the 2016 version of the WHO classification system to help determine the tumor grade. If the tumor is WHO grade I, evaluate the tumor under the criteria in listings 11.05 and 111.05. (See DI 34001.030 and DI 34005.111.) If the tumor is WHO grade II, evaluate the tumor under listing 13.13A3 or 113.13C. If the tumor is grade III or IV under the WHO or another classification system, consider the tumor to be highly malignant and evaluate it under the criteria in listings 13.13A1 or 13.13A2 and 113.13A or 113.13B. As in the 2007 version, the 2016 version of the WHO classification system is organized according to the cell type or anatomical structure of the central nervous system where the tumor originated.[9]

  

Table E. WHO Grade I Tumors

Type of tumor

Name of tumor

Grade of tumor

Other Astrocytic tumors

Pilocytic astrocytoma[10]

I

 

Subependymal giant cell astrocytoma

I

Ependymal tumors

Myxopapillary ependymoma

I

 

Subependymoma

I

Other Gliomas

Angiocentric glioma

I

Choroid Plexus tumors

Choroid plexus papilloma

I

Neuronal and Mixed Neuronal-glial tumors

Desmoplastic infantile astrocytoma and ganglioglioma

I

 

Dysembryoplastic neuroepithelial tumor (DNET)

I

 

Dysplastic gangliocytoma of the cerebellum (Lhermitte-Ducios)

I

 

Gangliocytoma

I

 

Papillary glioneuronal tumor

I

 

Paraganglioma of the filum terminale

I

 

Rosette-forming glioneuronal tumor of the fourth ventricle

I

Tumors of the Pineal Region

Pineocytoma

I

 

 

 

Tumors of Cranial and Paraspinal Nerves

 

Cellular schwannoma

I

 

Melanotic schwannoma

I

 

Plexiform schwannoma

I

 

Plexiform neurofibroma

I

 

Atypical neurofibroma

I

 

Perineurioma

I

 

Epithelioid peripheral nerve sheath tumor

I

Tumors of Meningiomas Cells

Meningioma

I

 

Meningothelial meningioma

I

 

Fibrous meningioma

I

 

Microcystic meningioma

I

 

Angiomatous meningioma

I

 

Psammomatous meningioma

I

 

Secretory meningioma

I

 

Lymphoplasmacyte-rich meningioma

I

 

Metaplastic meningioma

I

Mesenchymal, Non-Meningothelial tumors

Angiolipoma

I

 

Chondroma

I

 

Desmoid-type fibromatosis

I

 

Haemangioblastoma

I

 

Hibernoma

I

 

Leiomyoma

I

 

Lipoma

I

 

Osteochondroma

I

 

Osteoma

I

 

Rhabdomyoma

I

 

Solitary fibrous tumor of the dura/haemangiopericytoma[11]

I

Melanocytic lesions

Meningeal melanocytosis

I

 

Meningeal melanocytoma

I

Teratomas

Mature teratoma

I

Tumors of the Sellar Region

Adamantinomatous craniopharyngioma

I

 

Adamantinomatous craniopharyngioma

I

 

Papillary craniopharyngioma

I

 

Granular cell tumor

I

 

Papillary craniopharyngioma

I

 

Pituicytoma

I

 

Spindle cell oncocytoma

I

   

Table F. WHO Grade II Tumors

Type of tumor

Name of tumor

Grade of tumor

Diffuse Astrocytic and Oligodendroglial tumors

 

 

 

 

 

 

Diffuse astrocytoma, IDH-mutant

II

 

Diffuse astrocytoma, IDH-mutant, gemistocytic

II

 

Diffuse astrocytoma, IDH-wildtype

II

 

Diffuse astrocytoma, not otherwise specified (NOS)

II

 

Oligoastrocytoma, not otherwise specified (NOS)

II

 

Oligodendroglioma, IDH-mutant, 1p19q co-deleted

II

 

Oligodendroglioma, not otherwise specified (NOS)

II

Other Astrocytic tumors

Pilomyxoid astrocytoma

II

 

Pleomorphic xanthoastrocytoma

II

Ependymal tumors

Papillary

II

 

Clear cell

II

 

Tanycytic

II

 

RELA fusion-positive

II

Other gliomas

Chordoid glioma of the third ventricle

II

Choroid Plexus tumors

Atypical choroid plexus papilloma

II

Neuronal and Mixed Neuronal-glial tumors

Central neurocytoma

II

 

Cerebellar liponeurocytoma

II

 

Extraventricular neurocytoma

II

Tumors of the Pineal Region

Pineal parenchymal tumor of intermediate differentiation[12]

II

 

Papillary tumor[13]

II

Tumors of the Cranial and Paraspinal Nerves

Epithelioid malignant peripheral nerve sheath tumor (MPNST)[14]

II

 

MPNST with perineural differentiation

II

Tumors of Meningothelial cells

Atypical meningioma

II

 

Chordoid meningioma

II

 

Clear cell meningioma

II

Mesenchymal, Non-Meningothelial tumors

Solitary fibrous tumor of the dura/haemangiopericytoma

II

   

Table G. WHO Grade III Tumors

Type of tumor

Name of tumor

Grade of tumor

Diffuse Astrocytic and Oligodendroglial tumors

 

Anaplastic astrocytoma, IDH-mutant[15]

III

 

Anaplastic astrocytoma, not otherwise specified (NOS)

III

 

Anaplastic oligoastrocytoma, not otherwise specified (NOS)

III

 

Anaplastic oligodendroglioma, IDH mutant, 1p19q co-deleted

III

 

Anaplastic oligodendroglioma, not otherwise specified (NOS)

III

Other Astrocytic tumors

Anaplastic pleomorphic xanthoastrocytoma

III

Ependymal tumors

Anaplastic ependymoma

III

Choroid Plexus tumors

Choroid plexus carcinoma

III

Neuronal and Mixed Neuronal-Glial tumors

Anaplastic ganglioglioma

III

Tumors of the Pineal Region

Pineal parenchymal tumor of intermediate differentiation

III

 

Papillary tumor of the pineal region

III

Tumors of the Cranial and Paraspinal Nerves

Epithelioid malignant nerve sheath tumor (MPNST)

III

 

MPNST with perineural differentiation

III

Tumors of Meningothelial Cells

Atypical meningioma

III

 

Papillary meningioma

III

 

Rhabdoid meningioma

III

Mesenchymal, Non-Meningothelial tumors

Epithelioid haemangioendothelioma

III

 

Angiosarcoma

III

 

Liposarcoma (intracranial)

III

 

Ewing sarcoma/ETMR

III

 

Fibrosarcoma

III

 

Kaposi sarcoma

III

 

Leiomyosarcoma

III

 

Undifferentiated pleomorphic sarcoma/malignant fibrous histiocytoma

III

 

Rhabdomyosarcoma

III

 

Solitary fibrous tumor of the dura/haemangiopericytoma

III

   

Table H. WHO Grade IV Tumors

Type of tumor

Name of tumor

Grade of tumor

Glioblastoma

 

 

 

Glioblastoma, IDH wildtype

IV

 

Giant cell glioblastoma, IDH wildtype

IV

 

Gliosarcoma, IDH wildtype

IV

 

Glioblastoma, IDH mutant

IV

 

Glioblastoma, not otherwise specified (NOS)

IV

 

Diffuse midline glioma, H3K27M-mutant

IV

Tumors of the Pineal Region

Pineoblastoma

IV

Embryonal tumors

Medulloblastoma, WNT-activated

IV

 

Medulloblastoma, SHH-activated & TP53-mutant

IV

 

Medulloblastoma, SHH-activated & TP53 wildtype

IV

 

Medulloblastoma, classic

IV

 

Medulloblastoma, desmoplastic/nodular

IV

 

Medulloblastoma, extensive nodularity

IV

 

Medulloblastoma, large cell/anaplastic

IV

 

Medulloblastoma, not otherwise specified (NOS)

IV

 

CNS neuroblastoma

IV

 

CNS ganglioneuroblastoma

IV

 

Embryonal tumor with multilayer rosettes (ETMR), C19MC-altered

IV

 

Embryonal tumor with multilayer rosettes (ETMR), not otherwise specified (NOS)

IV

 

Medulloepithelioma

IV

 

Atypical teratoid/rhabdoid tumor

IV

 

CNS embryonal tumor, not otherwise specified (NOS)

IV

Tumors of Cranial and Paraspinal Nerves

Epithelioid malignant nerve sheath tumor

IV

 

MPNST with perineural differentiation

IV

Footnotes:

[1]

Louis, D.N., Ohgaki, H., Wiestler, O.D., Ellison & Cavenne, W.K., editors, (2007) WHO Classification of Tumours of the Central Nervous System, Fourth Edition, Lyon: International Agency for Research Centre.

[2]

Louis, D.N., Ohgaki, H., Wiestler, O.D. & Cavenne, W.K., editors, (2016) WHO Classification of Tumours of the Central Nervous System, Fourth Edition, Revised, Lyon: International Agency for Research Centre.

[3]

Includes juvenile pilocytic astrocytoma, a slower growing tumor that occurs mostly in children and young adults. The tumor forms in the brain more often than the spinal cord (see National Cancer Institute, http://www.cancer.gov/dictionary).

[4]

Some organizations and references, such as the National Cancer Institute, may classify pineocytoma as a grade II tumor. However, the WHO classification system lists pineocytoma as a grade I tumor. For the purposes of listings 13.13 and 113.13, we consider pineocytoma to be a grade I tumor.

[5]

Most meningiomas are benign and approximately 80 percent are treated successfully with surgery. Meningiomas represent 13 percent to 27 percent of all intracranial tumors and are more common in females and older age groups (see Marosi, C., Hassler, M., Roessler, K., Reni, M., Sant, M. Massa, E. & Vecht, C., (2008). Meningioma, Critical Reviews in Oncology/Hematology, 67(2), 153-171, doi: 10.1016/j.critrevonc.2008.01.010; and also Di Muzio, B. & Gaillard, F. (2018). Meningioma, Radiopaedia, available online at https://radiopaedia.org/articles/meningioma).

[6]

WHO grade III anaplastic astrocytoma and grade IV glioblastoma multiforme in the 2007 version of the WHO classification system include diffuse intrinsic brain stem gliomas, which are most common in children. The 2016 version of the WHO classification system replaces the term “glioblastoma multiforme” with the term “glioblastoma” and describes glioblastomas’ various subtypes.

[7]

The 2016 version of the WHO classification system does not use the term “primitive neuroectodermal tumor (PNET).” Instead, it lists these malignant tumors among the embryonal tumors. WHO made this change because molecular and genetic analysis of PNETs indicated this malignancy is comprised of two subtypes. These subtypes are “embryonal tumor with multilayer rosettes, C19MC-altered” and “embryonal tumor with multilayered rosettes, not otherwise specified (NOS)” (see Luijkx, T. & Jones, J. (2018). Primitive neuroectodermal tumour of the CNS, Radiopaedia, available online at https://radiopaedia.org/articles/primitive-neuroectodermal-tumour-of-the-cns).

[8]

Medulloblastomas are common in children, often occurring in early childhood. Adverse effects of radiation therapy for medulloblastomas include hearing loss, cognitive decline, endocrine abnormalities, and vascular complications (see Mueller, S. & Chang, S. (2009). Pediatric brain tumors: Current treatment strategies and future therapeutic approaches, Neurotherapeutics, 6(7), 570-586, doi: 10.1016/j.nurt.2009.04.006; and also Fortin, F. & Gaillard, F. (2018) Medulloblastoma, Radiopaedia, available online at https://radiopaedia.org/articles/medulloblastoma).

[9]

See Di Muzio, B. & Gaillard, F. (2018). WHO classification of CNS tumours, Radiopaedia, available online at https://radiopaedia.org/articles/who-classification-of-cns-tumours-1.

[10]

This benign tumor includes juvenile pilocytic astrocytoma, a slower growing tumor mostly in children and young adults. This tumor forms in the brain more often than the spinal cord (see National Cancer Institute, http://www.cancer.gov/dictionary). Juvenile pilocytic astrocytomas comprise 70-85 percent of all cerebellar astrocytomas (see Weerakkody, Y. & Gaillard, F., (2018). Pilocytic astrocytoma, Radiopaedia, available online at https://radiopaedia.org/articles/pilocytic-astrocytoma).

[11]

Solitary fibrous tumors of the dura/haemangiopericytoma can be grade I (benign), II, or III tumors.

[12]

Pineal parenchymal tumors of intermediate differentiation can be grade II or grade III tumors.

[13]

Papillary tumors of the pineal region can be grade II or grade III tumors.

[14]

Nerve sheath tumors can be grade II, III, or IV tumors.

[15]

WHO grade III anaplastic astrocytoma and grade IV glioblastoma include diffuse intrinsic brain stem gliomas, which are common in children.

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DI 24585.001 - Evaluation of Tumors of the Central Nervous System (tumors of the brain and spinal cord) - 07/24/2015
Batch run: 05/01/2018
Rev:07/24/2015