From the Guidelines
Occipital lobe DNET is a rare, benign brain tumor that specifically develops in the occipital lobe of the brain, which is the visual processing center located at the back of the brain. This tumor is classified as a low-grade (Grade I) glioneuronal tumor that typically affects children and young adults. DNETs are characterized by their slow growth, minimal invasiveness, and distinct appearance on imaging. These tumors often cause seizures as their primary symptom, particularly visual seizures given their occipital location, which may manifest as visual hallucinations, flashing lights, or temporary blindness. Other symptoms may include headaches, vision problems, or focal neurological deficits. Treatment typically involves surgical resection when possible, which often provides excellent seizure control and good long-term prognosis, as supported by the most recent guidelines for the diagnosis and treatment of brain tumors 1. Unlike many other brain tumors, DNETs rarely transform into malignant tumors, and complete surgical removal generally results in cure without the need for additional radiation or chemotherapy, as noted in the guidelines for the diagnosis and treatment of ependymal tumors 1. However, regular follow-up imaging is recommended to monitor for any recurrence. Some key points to consider in the management of DNETs include:
- The importance of accurate diagnosis and classification of the tumor, using histological and molecular diagnostic assessment of tissue specimens according to the World Health Organization (WHO) classification 2016 1
- The role of surgery as the crucial initial treatment in both children and adults, with the goal of achieving a gross total resection whenever possible 1
- The potential use of radiotherapy in certain cases, such as in pediatric patients with intracranial ependymomas of WHO grades II or III, or in adults with anaplastic ependymoma WHO grade III, or in case of incomplete resection of WHO grade II ependymoma 1
- The importance of regular follow-up imaging to monitor for any recurrence, as supported by the guidelines for the diagnosis and treatment of brain tumors 1
From the Research
Definition and Characteristics of Occipital DNET
- Occipital DNET is a type of dysembryoplastic neuroepithelial tumor (DNET) that occurs in the occipital lobe of the brain 2.
- DNETs are benign brain tumors that commonly present as childhood-onset temporal lobe epilepsy (TLE) 2, 3, 4, 5, 6.
- Occipital DNETs can present with seizures and may mimic temporal lobe epilepsy due to their chronic nature and ability to reorganize the network 2.
Clinical Presentation and Diagnosis
- Occipital DNETs can present with adult-onset temporal epilepsy, as shown in a case study where a patient presented with adult-onset temporal epilepsy and was found to have an occipital lesion on MRI 2.
- Diagnosis of occipital DNETs typically involves MRI, PET, and intracranial EEG to confirm the presence of the tumor and its location 2.
Treatment and Outcomes
- Surgical resection is a common treatment for DNETs, including occipital DNETs, and can be effective in achieving seizure freedom 3, 4, 6.
- The extent of resection is associated with seizure freedom, with greater extent of resection leading to better outcomes 3, 6.
- Seizure freedom rates after resection of DNETs have been reported to be around 86% at 1 year and 85% at 5 years, with complete or extended resection and extratemporal location being predictive of seizure freedom 6.