Metastases of primary CNS tumours
- Spread via CSF pathways (spinal Drop mets)
- High grade gliomas (10–25%)
- Primitive neuroectodermal tumors (PNET), especially medulloblastoma
- Ependymoma (11%)
- Choroid plexus tumors
- Pineal region tumors
- Germ cell tumors
- Pineocytoma
- Pineoblastoma
- Rarely:
- Oligodendrogliomas (≈ 1%)
- Hemangioblastomas
- Primary CNS melanoma
- Extraneural spread:
- Medulloblastoma (cerebellar-PNET): the most common primary responsible for extraneural spread. May spread to lung, bone marrow, lymph nodes, abdomen
- Meningioma: rarely goes to heart or lungs
- Malignant astrocytomas rarely metastasize systemically
- Ependymomas
- Pineoblastomas
- Meningeal sarcomas
- Choroid plexus tumours
- Tumours that spread through CSF pathways (see above) may spread via a CSF shunt (e.g. to peritoneum with VP shunt or haematogenously with a VA shunt); however, this risk is probably quite small
Differentiating Lymphoma vs GBM (Malikova et al 2016)
Features | Lymphoma | GBM |
Enhancement | Homogenously 64.8% | Nonhomogeneous 98.1% |
Necrosis | Present in 5.6% | Present in 88.9% |
Multiple lesion | Present in 51.9% | Present in 35.2% |
Optic pathways infiltration | Present in 42.6% | Present in 5.6% |
Other cranial nerve infiltration | 5.6% | 0% |
Bleeding | 5.6% | 44.4% |
Both supra and infratentorial localization | 27.7% | |
Basal ganglia involvement | 55.6% | 18.5% |
Cerebral cortex | 51.9% | 83.3% |
Differentiating | MRI | MRS | MR perfusion |
Tumefactive demyelination | 50% show enhancement, usually an open ring with in complete portion facing grey matter Mildy increased diffusion (unlike abscess) | Elevation glutamate/ glutamine peaks Reduced NAA Inc cho, lipid, lactate | No elevation in rCBV |
High grade glioma | Peripheral, heterogenous enhancement with nodules and necrosis Can be ring enhancing Solid parts diffusion restriction | Reduce NAA, Myoinositol Inc. Lipid, choline and lactate | Marked elevation rCBV |
Primary CNS lymphoma | Homogenous enhancement common Ring enhancing in HIV/immunocompromise Restricted diffusion (lower ADC then metastasis or HGG) | Large Choline peak Reversed Cho/Cr Ratio Markedly reduced NAA Lactate peak possible | Modest elevation rCBV |
Differential Diagnosis for Multiple Brain Lesions
Primary tumor | Multifocal glioma, tuberous sclerosis (giant cell astrocytoma), multiple meningiomas, lymphoma, rimitive neuroectodermal tumor, multiple neuromas (neurofibromatosis) |
Metastasis | Lung, Breast, Melanoma, Leukemia |
Infection | Bacterial, toxoplasmosis, Cryptococcus, aspergillosis, herpes simplex encephalitis |
Inflammation | Multiple sclerosis, tuberculosis gummas, granuloma, amyloidosis, sarcoidosis, vasculitis |
Vascular | Multiple hemorrhages, venous infarct, moyamoya disease, multiple strokes |
Other | Intracerebral calcifications, radiation necrosis |
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