Medulloblastoma vs Ependymoma and pilocytic astrocytoma
How to tell Medulloblastoma and Ependymoma and pilocytic astrocytoma apart when a board question makes them look alike.
Medulloblastoma is malignant vermis small-blue-cell with drop mets; ependymoma is ventricular pseudorosettes; pilocytic astrocytoma is cyst/mural nodule with Rosenthal fibers.
Side by side
Malignant pediatric cerebellar vermis tumor with truncal ataxia, hydrocephalus, small blue cells, Homer Wright rosettes, and CSF drop metastases.
Ependymoma arises near ventricles/4th ventricle with perivascular pseudorosettes; pilocytic astrocytoma is low-grade cerebellar cystic tumor with mural nodule and Rosenthal fibers.
Embryonal tumor of primitive neuroectodermal lineage grows in posterior fossa and can disseminate through CSF.
Ependymoma arises from ependymal lining; pilocytic astrocytoma is a circumscribed low-grade astrocytic tumor.
Midline vermis mass, Homer Wright rosettes, and drop metastases support medulloblastoma.
Perivascular pseudorosettes support ependymoma; Rosenthal fibers and cyst with mural nodule support pilocytic astrocytoma.
The trap
Posterior fossa tumors overlap in children, so histology, location, and CSF spread decide.
The repair move
For pediatric posterior fossa tumors, pair location with rosettes/fibers and CSF spread.
Try a free question
CoreA child has truncal ataxia, morning vomiting, hydrocephalus, a midline cerebellar vermis mass, Homer Wright rosettes, and spinal drop metastases. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Medulloblastoma. Pediatric vermis tumor with Homer Wright rosettes and CSF drop metastases supports medulloblastoma.
Why the other choices are tempting
- B. Ependymoma is ventricular/fourth-ventricle tumor with perivascular pseudorosettes.
- C. Pilocytic astrocytoma is often cystic with mural nodule and Rosenthal fibers.
- D. Meningioma is a dural-based adult tumor.
- E. Vestibular schwannoma is CPA nerve-sheath tumor with hearing loss.
Flashcards
Tap a card to flip it.
What posterior fossa tumor has drop metastases?
Medulloblastoma can spread through CSF and cause drop metastases.
What rosette points to medulloblastoma?
Homer Wright rosettes point to medulloblastoma.
Quick answers
What is the fastest way to tell Medulloblastoma from Ependymoma and pilocytic astrocytoma?
Medulloblastoma is malignant vermis small-blue-cell with drop mets; ependymoma is ventricular pseudorosettes; pilocytic astrocytoma is cyst/mural nodule with Rosenthal fibers.
What is the key clue for Medulloblastoma?
Malignant pediatric cerebellar vermis tumor with truncal ataxia, hydrocephalus, small blue cells, Homer Wright rosettes, and CSF drop metastases.
What is the key clue for Ependymoma and pilocytic astrocytoma?
Ependymoma arises near ventricles/4th ventricle with perivascular pseudorosettes; pilocytic astrocytoma is low-grade cerebellar cystic tumor with mural nodule and Rosenthal fibers.
What is the common trap with Medulloblastoma vs Ependymoma and pilocytic astrocytoma?
Posterior fossa tumors overlap in children, so histology, location, and CSF spread decide.