Rare Brain Tumor Linked To Seizures Has Good Outcomes

What was studied

This study looked at polymorphous low-grade neuroepithelial tumor of the young (PLNTY), a recently recognized brain tumor type linked with epilepsy. The researchers reviewed records from one medical center from 2014 to 2023 and identified 14 people with PLNTY who were treated with surgery. Their median age was 21.5 years, with ages ranging from 12 to 46, showing that this tumor can occur in adolescents and adults, not only in children.

The team used several kinds of information: clinical history, EEG, brain imaging, tumor tissue under the microscope, and molecular testing. They also compared some EEG findings in the PLNTY group with 26 people who had other low-grade epilepsy-associated tumors.

What they found

Most patients with PLNTY had difficult-to-control seizures before surgery. In 78.6% of patients, seizures were drug-resistant, and seizures had been present for a median of 4 years before surgery.

EEG and seizure-sign patterns were often bilateral or potentially misleading: 85.7% of PLNTY patients had bilateral interictal epileptiform discharges and/or mislateralizing or mislocalizing ictal EEG discharges and/or semiological signs, compared with 19.2% of patients with other low-grade epilepsy-associated tumors. On imaging, all tumors were supratentorial cortical solid or solid-cystic masses, most often in the temporal or temporo-occipital regions.

Under the microscope, the tumors had an infiltrative growth pattern, oligodendroglioma-like cells, strong and often diffuse CD34 staining, and frequent calcifications. A small number also had focal cortical dysplasia. Tumor proliferation activity was very low in nearly all cases. Molecular testing found BRAFV600E in 6 of 12 tested cases and FGFR3 fusion in 4 of 13 tested cases; no FGFR2 fusion was found in the 6 cases tested. After surgery, all patients had Engel class I seizure outcome.

Limits of the evidence

This was a small, retrospective study from a single center, with only 14 patients, so the results may not apply to all people with PLNTY. Because the study looked back at existing records, it can describe patterns but cannot determine the reasons for the EEG features or postsurgical outcomes.

Not every patient had every molecular test, so the reported frequencies of these gene changes are based on subsets of the cohort. The comparison group was limited to one set of other low-grade epilepsy-associated tumors, and the abstract does not provide details about follow-up length after surgery, so longer-term seizure outcomes are not described in the abstract.

For families and caregivers

For families, this study suggests that PLNTY is a rare brain tumor strongly associated with seizures and that it can affect adolescents and adults as well as younger patients. It may have EEG results that look bilateral or point to the wrong side or location, which could make presurgical evaluation more complex.

In this center's series, surgery was followed by excellent seizure outcomes by Engel classification. The molecular findings may help doctors better classify the tumor, but this study does not show how they should change treatment for an individual person.

What to watch next

Larger multicenter studies with longer follow-up and more complete molecular testing could help clarify how consistent these findings are across patients.

Terms in this summary

EEG

A test that records the brain's electrical activity.

drug-resistant seizures

Seizures that continue despite treatment with seizure medicines.

focal cortical dysplasia

An area of brain cortex that did not develop in the usual way and can be linked to seizures.

CD34 staining

A lab test on tumor tissue that shows whether a certain protein is present in the cells.

BRAFV600E

A change in the BRAF gene that can affect how cells grow.

FGFR3 fusion

A gene change where FGFR3 becomes joined to another gene, which can affect cell signaling and growth.

MAPK pathway

A cell signaling pathway involved in regulating cell activity and growth.

Engel class I

A category used to describe the best seizure outcome after epilepsy surgery.