From the Guidelines
Dysembryonic neuroepithelial tumors (DNTs) should be distinguished from other brain lesions using radiolabelled amino-acid compounds, such as [11C]MET, [18F]FET, or [18F]FDOPA, to guide surgical workup and ensure complete excision of the lesion, as this has a significant impact on patient care and postsurgical seizure outcome. When evaluating DNTs, it is essential to consider the clinical use of PET scans in the surgical workup of medically refractory epilepsy, as outlined in the recently published procedure guidelines by the clinical and nuclear imaging societies 1. The increased amino acid uptake in glioma is caused by an upregulation of the L-aminoacid transporter (LAT), and distinguishing between different pathologies has a significant impact on patient care. Some key points to consider when managing DNTs include:
- The primary clinical use of PET scans is to distinguish slowly progressing ambiguous and focal MRI lesions that may be caused by ganglioglioma or predominantly low-grade astrocytoma/oligodendroglioma from DNT or FCD 1.
- DNT and FCD show lower AA uptake than astrocytoma, oligodendroglioma, and ganglioglioma, but the literature is not sufficiently large to consistently separate the two groups 1.
- Approximately 30% of low-grade glioma are inactive using [18F]FET, and it may be in the same order for [11C]MET and [18F]FDOPA, while some DNT and FCD show up to moderately increased activity 1.
- A marked increased AA activity uptake strongly supports the neoplastic nature of a lesion, and the report of a particularly favourable diagnostic accuracy of [11C]MET (AUC: 0.95) may be caused by a disproportionately large fraction of glioma with an oligodendroglial component 1.
From the Research
Definition and Characteristics
- Dysembryoplastic neuroepithelial tumors (DNTs) are a type of brain tumor that belongs to the surgically treatable long-term epilepsy-associated group of tumors 2.
- DNTs are classified as neuronal and mixed neuronal-glial tumors (WHO grade I) and are usually seen in children and young adults 3.
- They are characterized by their unique morphology and are considered a surgically curable low-grade brain tumor 3.
Clinical Presentation
- DNTs often present with seizures, which can be resistant to anti-epileptic drugs 4.
- Seizures are a common symptom, occurring in almost 100% of cases, and can create significant long-term morbidity and disability 4.
- Other symptoms may include space-occupying lesions, as seen in an 8-year-old male child who presented with intractable seizures and a parieto-occipital space-occupying lesion 3.
Treatment and Outcomes
- Surgical resection of DNTs is effective in improving seizures and achieving long-term seizure freedom 4.
- Total gross resection of the lesion is the only factor statistically correlated with long-term seizure freedom 4.
- A prospective clinicopathologic and outcome study of 13 children with DNTs found that all children were seizure-free throughout postsurgical follow-up of 2-11 years after extended lesionectomy coupled with neuronavigation 5.
- Another study found that 83% of patients were seizure-free after surgical resection, and that complete tumor and EZ removal, short epilepsy duration, and lack of cortico-subcortical damage were the main prognostic factors for favorable outcome 2.
Surgical Strategies
- Surgical strategies for DNTs remain controversial, but early surgery is crucial in curing epilepsy 2.
- The extent of surgical resection may vary depending on the location and type of DNT, with more extensive resection recommended for temporal DNTs 6.
- A study found that complete lesionectomy alone was effective for long-term seizure control in children with extratemporal DNTs, but that extensive presurgical evaluations may be necessary for children with temporal DNTs 6.