Bilateral oligodendroglial hamartomas: A rare cause of drug-resistant epilepsy in a pediatric patient

Abstract

Intractable or drug-resistant seizures in pediatric patients are often secondary to cortical malformations, hamartomas, or mass lesions. Various subtypes of intracerebral hamartomas, associated with seizure disorders, have been described. In this report, we describe a subtype of intracerebral hamartoma associated with intractable epilepsy in a 10-year-old patient. Initial MR imaging demonstrated a mildly expansile, T2/FLAIR hyperintense, T1 isointense, nonenhancing lesion with blurring of the gray-white junction in the left amygdala. Surgical resection was performed, and pathology confirmed oligodendroglial hamartoma. Patient's seizures recurred after a two-year interval with imaging demonstrating a similar lesion in the right amygdala which in retrospect was also seen on multiple imaging studies. This case report demonstrates the importance of recognizing oligodendroglial hamartomas as a cause of intractable seizures given the imaging findings, distinguishing it from ganglioglioma, dysembryoplastic neuroepithelial tumor, and oligodendroglioma, and the importance of closely looking/searching for contralateral lesions, which has important therapeutic and prognostic implications.

Keywords: Epilepsy; Oligodendroglial hamartoma; Pediatric.

Figure 1:

(a) Ill-defined, expansile, T1 isointense, (b) T2 hyperintense, (c) Nonenhancing lesion within the left amygdala and hippocampus with blurring of the gray-white junction in the adjacent anteromedial temporal lobe (arrows). (d) Perfusion imaging demonstrates relative decrease in cerebral blood flow in the left temporal lobe.

Figure 2:

H&E images (at various magnifications) showing a cluster of oligodendrocytes with round nuclei and cytoplasmic clearings (arrows) in the subcortical white matter. Neurons with larger nuclei (relative to oligodendrocytes) can be seen in the adjacent cortex.

Figure 3:

(a) Status-post left anterior temporal lobectomy and left amygdalohippocampectomy with expected postsurgical changes. New ill-defined T1 isointense, (b) T2 FLAIR hyperintense, (c) and nonenhancing lesion in the right amygdala with blurring of the gray-white junction in the right inferomedial temporal lobe (arrows).

Figure 4:

(a) Preoperative imaging demonstrating subtle, ill-defined T2 hyperintense lesion within the right amygdala, (b) which appears increased in constituency on postsurgical T2 FLAIR (arrows).