Angiocentric Glioma, a rare long-term associated-epilepsy tumour

A 15-year-old male with a history of refractory epilepsy for the last three years. During the previous weeks, the patient had a gradual clinical worsening with frequent and prolonged seizures. The patient had no other relevant clinical history. The patient was submitted to an electroencephalogram (EEG) that revealed interictal and sporadic paroxysmal activity with a right superior frontal location.

MR imaging of the brain was performed and showed a cortico-subcortical right frontal lesion with ill-defined borders and local mass effect with enlargement of cortical gyri and effacement of adjacent sulci. The lesion revealed a subtle T1-hyperintense rim and T2 FLAIR hyperintensity. A T2 FLAIR hyperintense stalk-like extension to the right lateral ventricle was also present. Postcontrast enhancement and calcifications were absent. No focal cortical dysplasia was adjacent to the lesion. MRI imaging suggested the diagnosis of a low-grade glioma, and the patient was submitted to complete surgical excision.

Background and Clinical Perspective:

Angiocentric glioma was first described by Lellouch-Tubiana et al and Wang et al in 2005 and classified as a WHO grade I tumor in 2016 [1]. It is a rare subtype of neuroepithelial tumor primarily affecting pediatric patients and young adults and most frequently course with refractory epilepsy, being considered a long-term epilepsy-associated tumor (LEAT). Although less common, patients can also present headaches, ataxia and decreased vision. Focal neurological deficits are rare [2].

The diagnosis of angiocentric glioma relies on histology with the hallmark of angiocentric polarity with gliofibrillary acidic protein (GFAP) positive fusiform and bipolar astrocytic cells arranged around blood vessels in concentric sleeves and pseudo-rosettes. Immunohistochemical results are usually positive for GFAP, S-100 and vimentin. The Ki-67 proliferative index is generally ~1% [1].

Imaging Perspective:

Angiocentric gliomas will appear as an infiltrating lesion with ill-defined borders that involve the cortex and subcortical white matter. These lesions are predominantly supratentorial [1]. Even though angiocentric gliomas appear similar to low-grade gliomas on MRI imaging, a subtle T1-hyperintense rim is a typical finding, as well as a T2 FLAIR hyperintense stalk-like extension to the ventricle. These lesions usually cause local mass effect with enlargement of cortical gyri and effacement of adjacent sulci. Postcontrast enhancement and calcifications are typically absent. Focal cortical dysplasia can be present adjacent to the tumour [1, 2, 3].

Outcome:

Angiocentric gliomas tend to be slow-growing and non-malignant, and typically have a favourable prognosis, with low mortality and incidence of disability [1]. Surgical excision is usually curative. The degree of tumour resection is related to seizure control [3]. Adjuvant therapy such as radiation and chemotherapy is usually not required. Angiocentric gliomas arising in eloquent areas that are not suitable for surgical resection may require a stereotactic approach [4]. The optimal follow-up strategy is controversial as there is few data to establish the time to recurrence or the growth risk.

All patient data has been completely anonymised throughout the entire manuscript and related files.