CNS tumors

LEARNING OBJECTIVES

• Classify CNS tumors • Describe general characteristics of CNS

tumors• Identify tumor type in relation to age and

site of tumor• Describe primary peripheral nerve sheath

neoplasms with clinical relevance

FACTS

• Tumors in adults are more commonly based in anterior fossa/ supratentorial location whereas childhood tumors are more commonly posterior fossa/ infratentorial in location

• CNS tumors do not metastasize outside the brain and spinal cord.

• Even benign tumors can be sinister according to location.

Tumor origin

Tumor origin

• Neuronal• Glial• Nerve sheath• Meningeal• Others• Metastatic

CNS TUMOR CLASSIFICATION

• Primary tumors- 1/2 --3/4th • Metastatic tumors- 1/4 – ½• In primary tumors,WHO grading is done

according to biologic behaviour into grade I to IV (depending on risk of

recurrence)Under current classification scheme, lesions

of different grades are given distinct names

CNS TUMOR CLASSIFICATION• PRIMARY TUMORS

– Gliomas– Neuronal and glioneuronal tumors– Poorly differentiated tumors– Other parenchymal tumors

Primary lymphomas 1% of intracranial tumorsGerm cell tumors 0.2-1%

Pineal tumors

Tumors of meningesMeningiomas

Nerve sheath tumors SchwannomasNeurofibromas

PRIMARY TUMORS1-Gliomas

Astrocytomas (80% adult primary tumors)OligodendrogliomasEpendymomas and other paraventricular lesions

GradingAstrocytomas

Pilocytic astrocytoma(Non infiltrating)Grade IDiffuse astrocytoma- Grade IIAnaplastic astrocytoma- Grade IIIGlioblastoma multiforme- Grade IV

OligodendrogliomasMost Grade IIAnaplastic Grade III

EpendymomasMost Grade IIAnaplastic Grade III

Gliomas

• SITES and AGE group– Astrocytoma

• Pilocytic (Children , posterior fossa)• Infiltrating (Adults, Cerebral hemispheres)

– Oligodendroglioma• Adults 4th-5th decade, cerebral hemispheres

– Ependymoma (2 groups)• 4th ventricle, children• Intraspinal, adults

Low grade vs High grade glioma

Glioblastoma

Cystic/ Pilocytic astrocytoma

• Gliomas in children,are most common in the posterior fossa. Most childhood brain tumors arise below the tentorium, which is the reverse of the adult.

OLIGODENDROGLIOMA

Ependymoma

• Ependymoma arising from the ependymal lining of the fourth ventricle above the brainstem and bulging toward the cerebellum. Ependymomas are benign histologically.

Ependymoma• This horizontal

section of the brain reveals a large ependymoma of the fourth ventricle.

Ependymoma

Undifferentiated tumors

• Medulloblastoma– Predominantly in children (20% of brain

tumors in children)– Posterior fossa/ cerebellum– Highly malignant but radiosensitive

• Atypical teratoid/ rhabdoid tumor– Children less than 5 yrs– Dismal prognosis

Medulloblastoma• irregular posterior

fossa mass near the midline of the cerebellum and extending into the fourth ventricle in a child.

CNS TUMOR CLASSIFICATION

• METASTATIC TUMORS¼ to ½ of brain tumorsMainly mtastatic carcinomas5 common primaries accounting for 80% mets

– Breast– Lung– Skin (melanoma)– Kidney– GIT

Metastasis from a lung carcinoma. Metastases most often appear at the border of the grey and white matter in the distribution of the middle cerebral artery,

MENINGEAL TUMORS•Meningiomas-Grade I•Atypical meningiomas- Grade II•Anaplastic meningiomas-Grade III

Meningioma

Peripheral nerve sheath tumors

• Schwaanomas• Neurofibromas• Malignant peripheral nerve sheath tumors/

MPNST

Schwaanomas/ Acoustic neuromaThe mass lesion here is arising in the acoustic (eighth cranial) nerve at the cerebellopontine angle. This is a schwannoma. Patients may present with hearing loss. These benign neoplasms can be removed.

SUMMARY (Common tumors)

• Childhood tumors– Medulloblastomas, high grade– Pilocytic astrocytomas, Grade I– Ependymomas, posterior fossa(4th ventricle)– Choroid plexus papillomas, lateral ventricles

• Adult tumors• Gliomas• Spinal ependymomas, oligodendrogliomas

TUMORS of PNS

• NeurofibromaCutaneousPlexiform

• Schwaanoma• Malignant peripheral nerve sheath tumors

NEUROFIBROMA

PLEXIFORM NEUROFIBROMA

PLEXIFORM NEUROFIBROMA