Polymorphous low-grade neuroepithelial tumor of the young: case report and review focus on the radiological features and genetic alterations

Abstract

Background: A new type of epileptogenic tumor, the polymorphous low-grade neuroepithelial tumor of the young (PLNTY) was firstly reported by Jason T. Huse et al. at 2016. After that, only 1 case of PLNTY was reported by article. The radiological characteristics of PLNTY have not been concluded. The objective of our study was to report 3 cases of PLNTYs in details and to analyze the image characteristics and genetic alterations of PLNTYs by reviewing our cases and articles. Case presentation: There were 3 cases diagnosed as PLNTY by pathology in our hospital during the last 10 years, with the average age of 15. They were all suffered from different degrees of epilepsy. All of them underwent magnetic resonance (MR) imaging and 2 of them underwent computer tomography (CT) imaging. The PLNTYs are all appearing as a solid or solid-cystic cortical mass with little mass effect and unclear boundary with normal brain tissue. They are all shown as hyperintensity in T2WI and iso−/hypointensity in T1WI with slight or no enhancement after contract enhanced in MR imaging. The "salt and pepper sign" in T2WI and grit calcification in CT images might be specific characteristics of PLNTY. All of them recovered after excision of the tumors. The gene tests revealed fibroblast growth factor receptors 3 (FGFR3)-TACC3 fusion and FGFR3 amplification in one case, and the B-Raf proto-oncogene (BRAF) V600E mutation in another case. Conclusion: In the image, the partial ill-marginated cortical mass with "salt and pepper sign" in T2WI or grit calcification in CT imaging might be the typical imaging characteristics of PLNTY. We also prove that the BRAF V600E mutation as well as the FGFR2 and FGFR3 have a close relationship with PLNTY.

A “polymorphous low-grade neuroepithelial tumor of the young (PLNTY)” diagnosed in an adult. Report of a case and review of the literature

“…The unusual age of onset of the present case led us to critically perform a literature review and we found that, since its first description,[ 18 ] few cases of PLNTY have been reported in the English literature, mostly in the form of single case or small case series,[ 6 , 8 , 12 , 14 , 15 , 19 , 21 , 26 , 28 , 30 ] and almost all cases have been described in children and young adults;[ 6 , 8 , 12 , 14 , 15 , 19 , 21 , 28 , 30 ] the main findings of the literature review are summarized in [ Table 1 ]. Apart from the present case, to the best of our knowledge, only one case has been documented in a middle-aged adult patient by Riva et al .…”

“…[ 22 ] The term “polymorphous low-grade neuroepithelial tumor of the young (PLNTY)” indicates a recently introduced epileptogenic neoplasm, first described in 2017 by Huse et al .,[ 18 ] affecting children and young adults and almost invariably characterized by oligodendroglioma-like histological appearance, diffuse cluster of differentiation-34 (CD34) immunohistochemical expression, and MAP kinase pathway-related molecular aberrations. [ 18 ] Since then, few other cases of PLNTY have been reported in the literature,[ 6 , 8 , 12 , 14 , 15 , 19 , 21 , 26 , 28 , 30 ] all in the form of single case reports or short case series, and most of them included children or young adults. [ 6 , 8 , 12 , 14 , 15 , 19 , 21 , 28 , 30 ] The temporal lobe is the most frequently affected site and epilepsy is the most common presenting symptom.…”

“…[ 18 ] Since then, few other cases of PLNTY have been reported in the literature,[ 6 , 8 , 12 , 14 , 15 , 19 , 21 , 26 , 28 , 30 ] all in the form of single case reports or short case series, and most of them included children or young adults. [ 6 , 8 , 12 , 14 , 15 , 19 , 21 , 28 , 30 ] The temporal lobe is the most frequently affected site and epilepsy is the most common presenting symptom. [ 18 ] Histologically, despite being a morphologically heterogeneous tumor, PLNTY constantly shows an oligodendroglioma-like cell component, infiltrative growth pattern, and aberrant immunohistochemical staining for CD34.…”

BRAF V600E mutation mediates FDG-methionine uptake mismatch in polymorphous low-grade neuroepithelial tumor of the young

“…Thirty cases of PLNTY have been described to date, with the first ten reported by Huse et al in 2017 [ 3 , 5 , 9 , 10 , 16 , 21 , 27 , 28 ]; BRAF V600E mutation was seen in 14 of the patients and BRAF fusion in 1 patient. These BRAF alterations were mutually exclusive with other genomic events, including FGFR3 - TACC3 fusion, FGFR3 amplification, FGFR2 - CTNNA3 fusion, FGFR2 - INA fusion, FGFR2 - KIAA1598 fusion, FGFR2 rearrangement, and NTRK2 disruption, suggesting that the vast majority of PLNTYs are induced by BRAF mutation or FGFR fusion and subsequent MAPK activation.…”

“…Based on its histological and genomic profiles, cIMPACT-NOW Update 6 recommends PLNTY as a possible future classification for pediatric-type glial/glioneuronal tumors. However, because of their rare etiology, only a few PLNTYs have been described to date [3,5,9,10,16,21,27,28], and it is unclear how genomic alterations promote the pathogenesis of the disease. Herein, we present a case of PLNTY with unique metabolic imaging features.…”