Table 4. Summary table of embryonal tumors.
| *Neoplasm | Subtypes | Distinct imaging features | Locations | Histology and molecular | Grade (WHO) | Outcome |
|---|---|---|---|---|---|---|
| Medulloblastoma | WNT | Midline location with possible extension/origin from the pontocerebellar angle. Variable component of enhancement | Cerebellum (IV ventricle/vermis). Possible pontocerebellar angle location | Classic, rarely LCA, WNT signaling, MYC+ | ***IV | Good prognosis |
| SHH | Nodulariform/multinodular morphology or cerebellar folie “enlargement” associated with postcontrast enhancement | Cerebellar hemispheres/extra-axial extension | Desmoplastic/ **MBEN, SHH signaling, MYCN+ |
***IV | Good prognosis (infants), Intermediate (others) | |
| Group 3 | Avid contrast enhancement. Presence of CSF leptomeningeal spread at the onset | Cerebellum (Vermis/IV ventricle) | Classic/LCA, MYC+++ | IV | Poor prognosis | |
| Group 4 | Mild or absence of contrast enhancing. Presence of CSF leptomeningeal spread at the onset | Cerebellum (Vermis/IV ventricle) | Classic/LCA, Minimal MYC or MYCN | IV | Intermediate prognosis | |
| AT/RT | Currently not subgrouped. Future subclassifications are considered based on the distinct molecular features | Embryonal tumors with a more heterogeneous imaging presentation, commonly associated with calcification and areas of hemorrhage and necrosis in infants | Cerebellum (Vermis/IV ventricle) Extra-axial and intra-ventricular locations, supra and infratentorial tumors, and cranial nerve involvement may be already present on the onset |
Rhabdoid cells, SMARCB1, (INI1, SNF5, BAF47), SMARCA4, (BRG1), | IV | Poor prognosis |
*, Embryonal tumors are more often aggressive tumors located in the posterior fossa. There tumors are commonly hyperdense on CT scans. MR images show areas of restricted diffusion on DWI, hyperintensity on T1WI, and iso/hyperintensity on T2WI. Areas of enhancement on postcontrast T1WI vary and may be absent. **, MBEN, medulloblastoma with extensive nodularity – more common in infants. LCA, Large-cell anaplastic; ***, Although Grade IV more often these subtypes have a good prognosis. AT/RT, atypical teratoid/rhabdoid tumor.