Practical aspects regarding the histopathological grading and anaplastic transformation of gangliogliomas – a literature review

Abstract

Ganglioglioma represents a benign central nervous tumor, occurring predominantly in the pediatric population and affecting the temporal lobe. It is also renowned for its epileptogenic potential. However, to date, there are numerous uncertain features about this tumor, especially about its grading system. In the former World Health Organization (WHO) Classification of central nervous tumors system, gangliogliomas could have been attributed one out of three grades: grade I (benign), grade II (atypical), and grade III (anaplastic). The new classification systems have renounced to atypical ganglioglioma nomenclature, due to the lack of histopathological criteria for this entity. Another controversial aspect of grade I ganglioglioma is its potential to transform into a malignant tumor, namely, most frequently an anaplastic ganglioglioma. Based on our knowledge, there are no literature reviews to date focusing on anaplastic transformation potential. The present paper encompasses all anaplastic transformation of gangliogliomas and has analyzed the time frame between the two events, the age of the patients and its relationship to the complete or subtotal resection and administration of radiotherapy. Thirty-three cases of malignant transformation of ganglioglioma have been reported so far in the literature, with 54.54% of them undergoing progression to anaplastic ganglioglioma and 21.21% to anaplastic ganglioglioma. Median age was 26 years, and the cases were evenly distributed between the two genres. Only 27.27% of all evaluated cases had been administrated adjuvant radiotherapy, and only 44% of the latter have had an incomplete tumoral resection.

Infratentorial Relapsing Neuroglial Tumors in Adults: Management and Unsolved Issues—A Systematic Review

“…The effect of radiation on this group of tumors was usually considered to be limited since most are low-grade neoplasms [ 5 ]. High-grade lesions, including anaplastic ganglioglioma, liponeurocytoma and some central/extraventricular neurocytomas, may require adjuvant radiation therapy, as supported by conflicting literature findings [ 19 , 21 ].…”

“…Although a large retrospective meta-analysis showed that postoperative RT could significantly improve local control in patients with gangliogliomas who underwent STR, the benefit on overall survival (OS) was not observed [ 23 ]. Furthermore, many other studies reported that RT had little impact on progression-free survival (PFS) and OS [ 5 , 18 , 24 , 25 , 26 ]. A recent study by Lin and collaborators [ 4 ] showed that adjuvant RT may have a potentially adverse effect on survival in adult patients with low-grade gangliogliomas and that adjuvant chemotherapy has no positive effect on OS in operated patients.…”

“…The role of chemotherapy as an adjuvant treatment in neuroglial neoplasms still remains unknown, and it is usually reserved for grade II and III, similarly to radiation therapy [ 27 ], although little influence on prognosis was found [ 5 , 19 , 25 ]. Its potential use may be limited to children in whom radiotherapy is undesirable and patients with discouraging results after surgery and radiotherapy [ 23 , 28 ].…”

“…Typically described as well-circumscribed and slow-growing lesions, glioneuronal tumors are mostly supratentorial and temporally located [ 4 ]. Large-sized tumors may be reached before clinical recognition, and an age at diagnosis greater than 30 years old represents a rare clinical scenario [ 5 ]. While supratentorial neuroglial tumors are infrequent findings in adult populations, infratentorial, brainstem and intraventricular location are exceedingly rare [ 6 ].…”