Satellite lesions of DNET: implications for seizure and tumor control after resection

Dysembryoplastic neuroepithelial tumors (DNETs) are a common cause of chronic drug-resistant epilepsy and are known for their favorable surgical outcomes. Nevertheless, the seizure recurrence-free rate is not as favorable if tumorous nodules are present near the main mass. We call these small tumorous nodules in the vicinity of the main mass satellite lesions (SLs). We analyzed tumor and seizure control in the presence and following the subsequent removal of SLs.

We retrospectively reviewed the medical records, radiological data, and surgical procedures to obtain the outcomes of children who underwent resection surgery for DNET. The analyses were designed to address the associations among the demographic, tumor and seizure-related variables. A Cox proportional hazard model was used for the univariate and multivariate analyses.

In total, 39 consecutive patients were included (26 males and 13 females). SLs were found in 22 patients (56%). The year-to-year analysis of patients with Engel class I was approximately 80% during the follow-up period. However, the actual seizure recurrence-free survival (RFS) rate was 82, 73 and 70% at the first, second and fifth year, respectively. The patients who initially presented with SLs had 46% seizure recurrence rates, while those without SL had 18% seizure recurrence rates.

As the seizure-RFS rate significantly declines over time, a more accurate seizure-free rate analysis using survival curves could be important for determining the outcome of DNET surgery. A thorough review identifying satellite lesions preoperatively and using intraoperative neuronavigation, electrocorticography (ECoG) or intraoperative ultrasonography is warranted to accomplish the wide resection of tumors with accompanying satellite lesions.