Intraventricular central neurocytoma molecularly defined as extraventricular neurocytoma: a case representing the discrepancy between clinicopathological and molecular classifications

Abstract

Central neurocytoma (CN) is classically defined by its intraventricular location, neuronal/neurocytic differentiation, and histological resemblance to oligodendroglioma. Extraventricular neurocytoma (EVN) shares similar histological features with CN, while it distributes any site without contact with the ventricular system. CN and EVN have distinct methylation landscapes, and EVN has a signature fusion gene, FGFR1-TACC1. These characteristics distinguish between CN and EVN. A 30-year-old female underwent craniotomy and resection of a left intraventricular tumor at our institution. The histopathology demonstrated the classical findings of CN. Adjuvant irradiation with 60 Gy followed. No recurrence has been recorded for 25 years postoperatively. RNA sequencing revealed FGFR1-TACC1 fusion and methylation profile was discrepant with CN but compatible with EVN. We experienced a case of anatomically and histologically proven CN in the lateral ventricle. However, the FGFR1-TACC1 fusion gene and methylation profiling suggested the molecular diagnosis of EVN. The representative case was an “intraventricular” neurocytoma displaying molecular features of an “extraventricular” neurocytoma. Clinicopathological and molecular definitions have collided in our case and raised questions about the current definition of CN and EVN.

Two novel tumours with NTRK2 fusion in the methylation class of extraventricular neurocytomas, including one intraventricular

“…Additionally, 7/26 (27%) DNA‐methylation proven cases have no information concerning their precise location in the CNS [ 2 ]. Recently, Sato et al reported a left intraventricular tumour in a 30‐year‐old woman with histology suggestive of central neurocytoma (but the authors did not perform olig2 immunohitochemistry), FGFR1‐TACC1 fusion and a methylation score of 0.99 for the MC class of EVN [ 7 ]. This case and the current case 2 seem to suggest that a subset of tumours classified as MC EVN are not extraventricular.…”