Pediatric and elderly polymorphous low‐grade neuroepithelial tumor of the young: Typical and unusual case reports and literature review

Abstract

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY), one of the pediatric-type diffuse lowgrade gliomas, is characterized by a diffuse infiltrating pattern of oligodendroglioma-like tumor cells showing CD34 positivity and harbors mitogen-activated protein kinase (MAPK) alteration, such as vRAF murine sarcoma viral oncogene homolog B1 (BRAF) p.V600E or fibroblast growth factor fusion genetically. It occurs mainly in pediatric and adolescents with seizures due to the dominant location of the temporal lobe. However, there have been a few cases of PLNTY in adult patients, suggesting the wide range of this tumor spectrum. Here, we describe two cases of PLNTY, one in a 14-year-old female and the other in a 66-year-old female. The pediatric tumor showed typical clinical course and histopathology with BRAF p.V600E mutation, whereas the elderly tumor was unusual because of non-epileptic onset clinically and ependymal differentiation histopathologically harboring KIAA1549-BRAF fusion. There might be unusual but possible PLNTY, as in our elderly case. We also compared typical pediatric and unusual elderly tumors by reviewing the literature.

Polymorphous low-grade neuroepithelial tumor of the young with FGFR3-TACC3 fusion mimicking high-grade glioma: case report and series of high-grade correlates

“…The potential aggressiveness of PLNTY with FGFR-TACC fusion alterations contrasts the existing literature on PLNTY with BRAF V600E mutations. Although more often seen in adult male patients, BRAF V600E positive PLNTY cases have not demonstrated an increased propensity for recurrence or aggressiveness (39,40). Furthermore, our literature review (Table 1) generally supports a pathological correlation between BRAF V600E expression and a lower mitotic index (all <1%).…”

Systematic review and cumulative analysis of clinical properties of BRAF V600E mutations in PLNTY histological samples

“…Since the initial characterization of PLNTY, current understanding of the behavior and clinical outcomes associated with PLNTY has evolved. Notably, PLNTY is now known not to exclusively be a tumor of children and young adults, with reports of patients as old as 66 [3]. Although epilepsy is the most common symptom associated with PLNTY, not all patients present with a history of seizures.…”

“…Although epilepsy is the most common symptom associated with PLNTY, not all patients present with a history of seizures. Other presenting complaints include headache [1], [2], [4], psychiatric disturbances [2], [5], hallucinations and memory impairment [2], dizziness and neurological de cits [3], and visual disturbances [1]. Furthermore, although surgical resection is generally curative, cases have been reported of recurrence warranting resurgery [1], [6] and even recurrence with malignant transformation [7].…”

“…Primary outcome A multivariate logistic regression analysis (n = 62) was performed with whether or not a tumor carried a BRAF V600E mutation as the dependent variable and with predictors being patient sex, whether or not the patient was at least 18 years old, whether or not the tumor involved the temporal lobe, and whether or not the patient presented with seizures (Table 1). Consistent with prior reports [2], [3] A multivariate logistic regression analysis (n = 45) was performed with whether or not the patient achieved total seizure freedom postoperatively as the dependent variable and with the following predictors: whether or not the patient was ≥ 18 years of age, patient sex, whether or not the tumor involved the temporal lobe, and whether or not the tumor carried a BRAF V600E mutation (Table 2). BRAF V600E status was not found to be signi cantly associated with post-operative seizure freedom.…”

“…The nding that older age is associated with BRAF V600E mutations is consistent with the literature. Ida et al reported that, in their series, BRAF V600E-positive PLNTY tumors occurred in older patients, and a cumulative analysis by Furuta et al identi ed a signi cant association between patient age of at least 18 years and the BRAF V600E mutation [3].…”