Epilepsy-associated tumours: what epileptologists should know about neuropathology, terminology, and classification systems

Abstract

Brain tumours are an ever‐challenging issue in neurology and related medical disciplines. This applies in particular to brain tumours associated with childhood‐onset epilepsies, in which seizures are the presenting and only neurological symptom, as our current understanding of the biology and clinical behaviour of an individual tumour is far from being evidence‐based. Prospective and randomized clinical trials are lacking in the field of epilepsy‐associated tumours and a review of the current literature evokes more questions than provides answers. In this review, current areas of controversy in neuropathology, as well as terminology and classification, are discussed from an epileptologist's perspective. An illustrative case report exemplifies this controversy to further promote interdisciplinary discussion and novel research avenues towards comprehensive patient management in the near future.

Epilepsy surgery of “low grade epilepsy associated neuroepithelial tumors”: A retrospective nationwide Italian study

“…On the other hand, assessment of drug responsiveness may necessitate at least 1 year of observation. 6,7,12,[14][15][16][17][18]23 In fact, although LEATs are usually considered to have a benign indolent behavior, several reports have demonstrated that gangliogliomas (GGs) 3,9,13 and some glial tumors, such as pleomorphic xanthoastrocytoma (PXA), 3,24 may exhibit an evolving course or malignant transformation. 22 Furthermore, in the field of LEATs, where a correct histologic and molecular diagnosis is increasingly important, avoiding loss of time is essential, for epileptologic, neuropsychological, and oncologic reasons.…”

“…1,3,26,27 The group of LEATs is currently enlarging due to newly recognized, often rare, histotypes, such as PXA, angiocentric glioma (AG), papillary glioneuronal tumor (PGNT), extraventricular neurocytoma, 3 • Interobserver variability, surgical strategy (tailored resection), and anatomic site (temporal lobe) are factors related to the incidence of FCD detection • A timely surgical treatment, oriented to optimize epileptologic, neuropsychological, and oncologic outcome should be nowadays warranted and/or mixed features (GG and DNET, PXA and GG, PXA and DNET). 18,23,24,29,30 Knowledge about molecular features of diffuse gliomas 24 and LEATs has grown rapidly. 18,23,24,29,30 Knowledge about molecular features of diffuse gliomas 24 and LEATs has grown rapidly.…”

“…3,28 There is ongoing debate on improving consensus for histopathologic diagnosis. 3,18,23,[29][30][31][32][33][34] LEATs show v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations in a wide percentage of cases, 3,18,23,[30][31][32][33][34] and mutant BRAFV600E protein in gangliogliomas is expressed predominantly by neuronal tumor cells. 3,18,23,[29][30][31][32][33][34] LEATs show v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations in a wide percentage of cases, 3,18,23,[30][31][32][33][34] and mutant BRAFV600E protein in gangliogliomas is expressed predominantly by neuronal tumor cells.…”

“…18,23,24,29,30 Knowledge about molecular features of diffuse gliomas 24 and LEATs has grown rapidly. 32 Characterizing molecular signatures could be very helpful, allowing a more precise histologic definition and a better comprehension of both oncologic behavior 3,14,15,18,23,29,30,33 and the epileptologic mechanisms involved. 32 Characterizing molecular signatures could be very helpful, allowing a more precise histologic definition and a better comprehension of both oncologic behavior 3,14,15,18,23,29,30,33 and the epileptologic mechanisms involved.…”

“…32 Characterizing molecular signatures could be very helpful, allowing a more precise histologic definition and a better comprehension of both oncologic behavior 3,14,15,18,23,29,30,33 and the epileptologic mechanisms involved. 3,5,6,10,13,16,23,25 However, extremely wide and hardly explicable variable percentages of association of LEATs and FCD, ranging from 0 to 80%, 3,5,6,10,13,16,23,25 have been reported so far. 3,5,6,10,13,16,23,25 However, extremely wide and hardly explicable variable percentages of association of LEATs and FCD, ranging from 0 to 80%, 3,5,6,10,13,16,23,25 have been reported so far.…”