CNS tumors

LEARNING OBJECTIVESClassify CNS tumors Describe general characteristics of CNS tumorsIdentify tumor type in relation to age and site of tumorDescribe primary peripheral nerve sheath neoplasms with clinical relevance

FACTSTumors in adults are more commonly based in anterior fossa/ supratentorial location whereas childhood tumors are more commonly posterior fossa/ infratentorial in locationCNS tumors do not metastasize outside the brain and spinal cord.Even benign tumors can be sinister according to location.

Tumor origin

Tumor originNeuronalGlialNerve sheathMeningealOthersMetastatic

CNS TUMOR CLASSIFICATIONPrimary tumors- 1/2 --3/4th Metastatic tumors-1/4 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 CLASSIFICATIONPRIMARY TUMORSGliomasNeuronal and glioneuronal tumorsPoorly differentiated tumorsOther parenchymal tumorsPrimary lymphomas 1% of intracranial tumorsGerm cell tumors 0.2-1%Pineal tumors

Tumors of meningesMeningiomas

Nerve sheath tumors SchwannomasNeurofibromas

PRIMARY TUMORS

1-GliomasAstrocytomas (80% adult primary tumors)OligodendrogliomasEpendymomas and other paraventricular lesions

GradingAstrocytomasPilocytic astrocytoma(Non infiltrating)Grade IDiffuse astrocytoma- Grade IIAnaplastic astrocytoma- Grade IIIGlioblastoma multiforme-Grade IVOligodendrogliomasMostGrade IIAnaplasticGrade IIIEpendymomasMostGrade IIAnaplasticGrade III

GliomasSITES and AGE groupAstrocytomaPilocytic (Children , posterior fossa)Infiltrating (Adults, Cerebral hemispheres)OligodendrogliomaAdults 4th-5th decade, cerebral hemispheresEpendymoma (2 groups)4th ventricle, childrenIntraspinal, adults

Low grade vs High grade glioma

Glioblastoma

Cystic/ Pilocytic astrocytomaGliomas 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

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

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

Ependymoma

Undifferentiated tumorsMedulloblastomaPredominantly in children (20% of brain tumors in children)Posterior fossa/ cerebellumHighly malignant but radiosensitiveAtypical teratoid/ rhabdoid tumorChildren less than 5 yrsDismal prognosis

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

CNS TUMOR CLASSIFICATIONMETASTATIC TUMORS to of brain tumorsMainly mtastatic carcinomas5 common primaries accounting for 80% metsBreastLungSkin (melanoma)KidneyGIT

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 TUMORSMeningiomas-Grade IAtypical meningiomas- Grade IIAnaplastic meningiomas-Grade III

Meningioma

Peripheral nerve sheath tumorsSchwaanomasNeurofibromasMalignant 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 tumorsMedulloblastomas, high gradePilocytic astrocytomas, Grade IEpendymomas, posterior fossa(4th ventricle)Choroid plexus papillomas, lateral ventricles

Adult tumorsGliomasSpinal ependymomas, oligodendrogliomas

TUMORS of PNSNeurofibromaCutaneousPlexiformSchwaanomaMalignant peripheral nerve sheath tumors

NEUROFIBROMA

PLEXIFORM NEUROFIBROMA

PLEXIFORM NEUROFIBROMA