Adult‐onset angiocentric glioma of epithelioid cell‐predominant type of the mesial temporal lobe suggestive of a rare but distinct clinicopathological subset within a spectrum of angiocentric cortical ependymal tumors

Abstract

Angiocentric glioma (AG) is defined as an epilepsy-associated stable or slowly growing cerebral tumor primarily affecting children and young adults, histologically consisting mainly of monomorphic, bipolar spindle-shaped cells and occasional round to monopolar columnar epithelioid cells, showing angiocentric growth pattern and features of ependymal differentiation. We describe two clinicopathologically unusual cases of AG. Case 1 is a 54-year-old woman with a 10-year history of complex partial seizures. MRI revealed non-enhancing T1-low, T2/fluid-attenuated inversion recovery (FLAIR)-high intensity signal change in the left hippocampus and amygdala. After selective amygdalohippocampectomy, she had rare non-disabling seizures on medication for over 50 months (Engel's class I). Case 2 is a 37-year-old man with a 3-year history of complex partial seizures. MRI revealed non-enhancing T1-low, T2/FLAIR-high intensity signal change in the left uncus and amygdala. After combined amygdalohippocampectomy and anterior temporal lobectomy, he has been seizure-free for over 11 months. Histologically the tumors in both cases consisted mainly of infiltrating epithelioid cells (GFAP- ∼±, S-100-) with perinuclear epithelial membrane antigen (EMA)-positive dots and rings, showing conspicuous single- and multi-layered angiocentric arrangements. Occasional tumor cells showed spindle-shaped morphology (GFAP+, S-100+) with rare EMA-positive dots aligned radially and longitudinally along parenchymal blood vessels. Focal solid areas showed a Schwannoma-like fascicular arrangement with rare EMA-positive dots and/or sheets of epithelioid cells with abundant EMA dots. Electron microscopic investigation demonstrated features of ependymal differentiation. These cases, together with a few similar cases previously reported, appear to represent a rare but distinct clinicopathological subset of AG characterized by adult-onset, mesial temporal lobe localization and epithelioid cell-predominant histology.

Seizure outcome in surgically treated drug-resistant mesial temporal lobe epilepsy based on the recent histopathological classifications

“…2 The analysis of outcome in the different types of ELGT found in our patients is significantly limited by the small number of cases in each histopathological subtype; represented mainly by glioneuronal tumors, is currently enlarging not only for the recognition of new, often rare, histotypes but also for the continuous identification of tumors having hybrid or mixed features that suggest the existence of a histological spectrum that can be difficult to categorize. 43,54,67,73,74,91 In addition, in our series the association between ELGT and FCD was observed in 53% of cases, confirming previous studies reporting this association in 40%-80% of cases. The new class, FCD Type IIIb, which includes cases with abnormal cortical layering (called FCD Type I when alone) associated with ELGT, has been introduced by the recent ILAE FCD classification.…”

Morphological and molecular features of astroblastoma, includingBRAFV600Emutations, suggest an ontological relationship to other cortical-based gliomas of children and young adults

“…33,34 Furthermore, in addition to radially oriented monopolar perivascular cells as seen in ABs and ependymomas, AGs also show circumferentially and longitudinally oriented perivascular growth patterns, which are absent in AB. Finally, AGs have been reported to be Olig2 negative 31,32 and lack BRAF V600E mutations or the vascular hyalinization commonly seen in AB. [33][34][35] Rare reported cases of AG with astroblastoma-like features and/or increased mitotic activity 34,36 should thus be reexamined, immunostained for Olig2, and tested for BRAF mutations.…”

Angiocentric glioma: the infiltrative glioma with ependymal differentiation

“…The total number of reported cases in the English literature is currently still less than 50 (2,(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). It is most commonly encountered in early adulthood or childhood but a few late onset cases have also been reported (12,(13)(14)(15)(16)(17)(18)(19)(20)(21).…”