Angiocentric glioma, WHO grade I
Angiocentric glioma (AG) was described by two different groups and with two different names as a distinctive epileptogenic neoplasm. Due to the features of an infiltrating astrocytoma and ependymoma at histopathological, immunohistochemical and ultrastructural level, Wan et al proposed the term monomorphous angiocentric glioma (1). Lellouch-Tubian et al reported the presence of a neuronal cell component in all cases of their series and thus classified this tumor type as a mixed glioneuronal neoplasm and used the term angiocentric neuroepithelial tumor (2). Accordingly, this tumor was recognized as a distinct entity in the 2007 WHO classification and named as angiocentric glioma within the category of 'Other Neuroepithelial Tumours' (3). Due to its benign clinical behavior and the possibility of curative surgery, the neoplasm was assigned to WHO grade I (3). Among the cases of angiocentric glioma, seizure was the most common symptom at presentation (1-6). Evidence of adjacent malformation of cortical development/focal cortical dysplasia has been reported in a subset of angiocentric gliomas, suggesting a developmental basis to their origin (5,7). Magnetic resonance imaging of AGs demonstrated supratentorial, non-enhancing, T1-hypointense, T2-hyperintense lesions (1-6). Gross-total resection of this lesion yields excellent results (1-6).
The molecular genetic properties of angiocentric gliomas have not been fully studied. One tumor showed loss at 6q24-q25 by classic CGH, while another showed a gain at 11p11.2 by high resolution array CGH (6). In a recent study of three cases, all tumors showed wild genotype for the IDH1, IDH2 and BRAF V600E genes (8).
Several types of neuroepithelial tumors are known as the cause of intractable epilepsy (7,9). They are generally slow growing, low-grade, cortically based tumors, with indolent course and in many cases they exhibit neuronal in addition to glial differentiation. Gangliogliomas and dysembryoplastic neuroepithelial tumors (DNT) predominate in this group, followed by pleomorphic xanthoastrocytoma, papillary glioneuronal tumor and angiocentric glioma (9).
Histopathological differential diagnosis of angiocentric glioma constantly displaying angiocentric orientation of spindle-shaped cells includes ependymoma, astroblastoma, infiltrating astrocytoma, and dysembryoplastic neuroepithelial tumor.
Though the incidence of angiocentric glioma is not known, most of the reported cases have presented with chronic epilepsy; and despite reports of rare examples with increased mitotic activity (10) or anaplastic features (11), excision alone has most often proved curative. As always, accurate pathological diagnosis is important to prevent overtreatment.
Contributed by Figen Soylemezoglu, Cigdem Himmetoglu, Kader K Oguz, Serap Saygi, Nejat Akalan