Polymorphous low-grade neuroepithelial tumor of the young.

Background: Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a newly recognized entity first described in 2017. This article reports the clinical, radiological, histological, and molecular characteristics of PLNTY diagnosed in a young female.

Case description: A 20-year-old female, not known to have any medical illness, presented to the emergency department with speech arrest that progressed to generalized tonic-clonic seizures. Brain magnetic resonance imaging showed a T2 hyperintense nonenhancing cortical-based heterogeneous mass in the left medial temporal lobe and adjacent inferior temporal gyrus measuring 2.7 × 2 × 2.5 cm with no susceptibility signal or diffusion restriction. Electroencephalogram (EEG) showed left temporal epileptiform discharges. She underwent left frontotemporal craniotomy and tumor resection. The light microscopic examination of the tumor revealed a low-grade infiltrative neoplasm. There was a classical appearance of round cells with perinuclear halo, immunopositive for olig-2, glial fibrillary acidic protein (GFAP), and cluster of differentiation-34. There was B-Raf protooncogene, serine/threonine kinase (BRAF) c.1799T>A (p.V600E) point mutation and absence of isocitrate dehydrogenase (IDH) 1 and 2 hotspot mutations. The overall findings were diagnostic of PLNTY.

Conclusion: This article reports an additional case of PLNTY, a newly defined central nervous system tumor entity, describing its clinical, radiological, histological, and molecular features.