Central Nervous System Masses Part 2
Review of CNS masses for radiology board preparation. Prepare to succeed!
Show Notes/Study Guide:
Do pituitary adenomas enhance more rapidly or slower compared to normal brain?
Pituitary adenomas enhance more slowly compared to normal brain.
What are common differences between craniopharyngiomas in an adult vs craniopharyngiomas in a child?
Adult: Papillary type which does not calcify. Is a capsulated lesion so it is easier to resect. More solid lesion.
Peds: Adamantinomatous type which does calcify. May not be capsulated and is harder to resect. “Machinery oil” appearance. More cystic lesion.
Similarities: Both are partially solid and cystic lesions low grade lesions in sellar/suprasellar region.
Meningiomas classically show uptake on what nuclear medicine studies?
Meningiomas typically have uptake with Tc-MDP (bone scan agent) and octreotide and Ga68-Dotatate.
What are common differences between a CNS dermoid cyst and epidermoid cyst?
Epidermoid: can be congenital or acquired after LP/trauma. Usually located off midline. Follow CSF intensity.
Dermoid: Typically located at midline with internal lipoid material, fat density on CT, bright on T1 weighted images, NF2 association.
If you see what looks like a meningioma but there is associated bony invasion of the skull, what additional entity should be considered?
Hemangiopericytoma: a soft tissue sarcoma that can mimic an aggressive meningioma. These typically do not calcify or cause hyperostosis, but these do often invade the calvarium. If you see invasion of the calvarium, imaging cannot differentiate between a meningioma or a hemangiopericytoma.
In what age group to atypical teratoma/rhabdoid (AT/RT) tumors most commonly present?
Pediatrics, < 6 years of age and often < 2 years of age. AT/RT tumors are high grade often large tumors with internal necrosis and heterogeneous enhancement which may be in a supra- or infra-tentorial location but are most common in the cerebellum. Cannot tell difference on imaging between a medulloblastoma and AT/RT so this is a pathologic diagnosis.
Are desmoplastic infantile gliomas more commonly supratentorial or infratentorial?
Desmoplastic infantile gliomas (DIGs) are classically supratentorial-only lesions. These are large, cystic tumors in a superficial cortical location. Commonly present with rapidly increasing head circumference before first birthday.
What is the most common location of both a choroid plexus papilloma/carcinoma in pediatric patients and in adults?
Pediatrics: Supratentorial location in lateral ventricle.
Adults: Infratentorial location in 4th ventricle
What is the most common brain metastasis in pediatric patients?
Neuroblastoma. Three common sites of metastatic disease with neuroblastoma are the bones, the dura/brain, and the posterolateral orbit.
If you see a cyst with mural nodule in the temporal lobe of a teenager with epilepsy which tumor(s) should you think of first?
First is probably a ganglioglioma which may present with a cystic and solid mass with calcifications essentially anywhere in any age range, but classic is with a temporal lobe mass in setting of temporal lobe epilepsy. Differential includes other cortical based tumors; remember DOG for cortical-based tumors (DNET, Oligodendroglioma, Ganglioglioma). Note ganglioglioma is different from a desmoplastic infantile glioma and classic history for the latter is rapid head enlargement in a pediatric patient < 1 year of age). Note also that you can’t tell a DNET from a ganglioglioma on imaging.
What is the most common location for a pleomorphic xanthroastrocytoma (PXA)?
PXA’s ae always supratentorial, usually located in the temporal lobe, presenting with a cyst with mural nodule. This may have a dural tail and is also common in setting of seizures.
True or false? A PNET (primitive neuroectodermal tumor) appears similarly on histology as a medulloblastoma?
True. These entities can look very similar on histology. However, a PNET is a supratentorial lesion and have been nicknamed a “supratentorial medulloblastoma”. Bad prognosis with PNET due to propensity for distant metastases.
What is the classic imaging appearance of a medulloblastoma?
Medulloblastomas commonly present as a midline mass centered at the roof of the 4th ventricle with associated hydrocephalus.
What tumor is classically associated with gelastic seizures and precocious puberty, with a mass of the tuber cinereum?
Hypothalamic hamartoma. This is a hamartoma of the tuber cinereum. Typically, do not enhance. This is separate in location from the pituitary stalk.
Note—a gelastic seizure is a seizure with sudden onset of laughing or other sudden release of energy.
What is more common in the spine—medulloblastoma or ependymoma?
What episode states: Medulloblastoma is much more common than ependymoma. Medulloblastomas of the spine tend to restrict on DWI and have zuckerguss (sugar icing) appearance with leptomeningeal spread/coating of disease. Ependymomas are more likely to calcify than medulloblastomas.
Correction: The question “What is more common in the spine—medulloblastoma or ependymoma?” contains an incorrect answer “Medulloblastoma is much more common than ependymoma.” Approximately 350 cases of medulloblastoma are diagnosed annually compared to approximately 1300 cases of ependymoma per year. About 10% of ependymomas are found in the spinal cord compared to up to 33% of medulloblastomas involving the leptomeninges of the spinal cord. Therefore, involvement of the spinal cord is likely more common in ependymoma.
Can you name at least one syndrome with a medulloblastoma association?
Perhaps top two are basal cell nevus syndrome (Gorlin syndrome) which presents with medulloblastoma and dural calcifications, basal cell skin cancers, odontogenic cysts, common in post-radiation state. Also, Turcot syndrome (discussed in episode 1) are classic for GI polyposis and brain tumor to include medulloblastoma and/or glioblastoma.
With a vertical gaze palsy (dorsal Parinaud syndrome) what tumor is most classic?
A pineal tumor.
What is the most common pineal tumor?
A germinoma is the most common pineal tumor (only classically seen in boys). In general, girls are much more likely to have suprasellar germinomas and boys are most likely to have pineal germinomas. Germinomas can cause precocious puberty via HCG secretion.
Can you name some other pineal region tumors? What are some differences between these?
Besides pineal germinoma, there is also pineocytoma (uncommon in childhood, non-invasive, children “hide out of cyt (sight)”), pineoblastoma (common in childhood, “kids frequently have a blast”, highly invasive).
What is the so-called “trilateral retinoblastoma”?
This is when you have bilateral retinoblastomas and a concurrent pineoblastoma as these tumors are associated with one another. Both are small round blue cell tumors.
What is the significance of pineal calcifications in differentiating between a germinoma versus pineocytoma/pineoblastoma?
If pineal calcifications appear “exploded” it is a pineoBLASToma/cytoma. If pineal calcifications appear engulfed, it is more likely a pineal germinoma.
