BRAIN TUMOURS

                  CLASSIFICATION OF BRAIN TUMOURS
              
                   METASTATIC BRAIN TUMOURS

BRAIN METASTASIS

·         Hematogenous origin

·         Most common site of origin:- Lung Ca>Breast Ca>Melanoma (Melanoma has greatest tendency to metastasize to brain with brain metastasis present in 80% cases of melanoma at time of autopsy)

·         Most common site of Metastatic Growth- ‘Grey mater-White mater junction’

·         Most common cause of hemorrhagic metastasis:- Lung Ca (Although, melanoma may have greatest tendency to hemorrhage)

·         Δsis- Best investigation- Contrast enhanced MRI

Appearance- ‘Well circumscribed lesions with adjacent edema’

·         Rx-

o   Best Rx- Surgical removal of brain metastasis followed by WBRT (Whole Brain Radio-Therapy)

o   Radiotherapy- (mostly palliative)

1.       WBRT (Whole Brain Radio-Therapy)

2.       SRS (Stereotactic Radio-Surgery)- Can be done only in:-

·         Lesions <4 cm in diameter

·         1-3 metastasis only

o   SRS is better than WBRT in-

1.       Local control of disease

2.       Sometimes curative

o   Chemotherapy-

1.       Anti-Angiogenic Drugs- Bevacizumab (can be used only in patients with Lung Ca metastasis with EGFR mutations)

LEPTOMENINGEAL METASTASIS a.k.a MENINGEAL CARCINOMATOSIS

·         Most common site of origin:- Breast Ca>Lung Ca>Melanoma>Hematological (Acute leukemia>diffuse lymphoma)

·         Hematological spread

·         Most common site of metastasis- Subarachnoid space

·         Δsis-

o   MRI

o   Demonstration of tumour cells in CSF (definitive but ↓sensitive)

·         Rx- only Palliative- Radiotherapy

EPIDURAL METASTASIS

·         Most common site of origin:- Breast ca>Prostate Ca

·         Most common site of metastasis:- Thoracic spine>Lumbar spine>Cervical spine

·         Δsis- MRI

·         Rx- Immediate Surgical Resection followed by Radiotherapy

                           

                              PRIMARY BRAIN TUMOURS

                                        

                                                   GLIOMAS

ASTROCYTOMAS

·         WHO Prognostic Grading (Based on Histology)

GRADE	FEATURES
LOW GRADE
I	PILOCYTIC ASTROCYTOMA/ SUBEPENDYMAL GIANT CELL ASTROCYTOMA ·         Most common site- Cerebellum ·         Most common presentation- cystic lesions with enhancing mural nodule ·         Predominantly seen in childhood ·         Rx- Surgical Resection/ Inhibitors of mTOR (Mammalian Target of Rapamycin)
II	·         Clinical presentation- Seizures in young adults ·         On MRI- non-enhancing tumours with ↑T2/FLAIR signal
HIGH GRADE
III	ANAPLASTIC ASTROCYTOMA ·         Present in 40-60 yrs.
IV	GLIOBLASTOMA ·         Most common High grade tumour. ·         Most common cause of primary malignant brain tumours. ·         60-80 yrs ·         Histology- ‘Pseudopalisading’ & ‘Glomeruloid Body’( vascular proliferation forms tuft-like structure) ·         High Infiltrative ·         MRI- ‘Ring enhancing masses with central necrosis and surrounding edema’ ·         Rx- Maximal Surgical Resection followed by Partial Field External Beam Radiotherapy + Temozolamide (Oral Alkylating agent) followed by 6-12 months of adjuvant Temozolamide

·         Prognostic Factors-

o   Old age

o   Histological features

o   Poor Karnofsky performance status

o   Resectability of Tumour

o   MGMT promoter expression

OLIGODENDROGLIOMA

·         On histology- ‘Fried Egg’ appearance due to perinuclear clearing + reticular pattern of blood vessel growth.

·         Both Grade II & III show del(1p) & del(19q), therefore, are sensitive to chemotherapy  (Procarbazine, Lomustine, Vincristine) and radiotherapy.