The Expanding Family of Glioneuronal Tumors

Abstract

Three new entities have been recently added to the group of glioneuronal tumors in the most recent update of the World Health Organization classification of tumors of the central nervous system: papillary glioneuronal tumor, rosetted glioneuronal tumor with neuropil-like islands, and rosette-forming glioneuronal tumor of the fourth ventricle. These tumors are relatively infrequent lesions, and because of that, they can be challenging to diagnose for the practicing pathologist. In this article, we summarize the clinical and pathologic findings of these new lesions.

Spinal cord glioneuronal tumor with neuropil-like islands with 1p/19q deletion in an adult with low-grade cerebral oligodendroglioma

“…Oligodendrocyte-like cells, which may express the neuronal markers NeuN and Hu, exist within or around these islands; mature-appearing neurons may also be present [2]. These islands typically punctuate a background of GFAPpositive fibrillary, gemistocytic, or protoplasmic elements characteristic of astrocytoma [1]. Since this tumor's initial description [3], approximately 25 cases of GTNI have been published (Table 1).…”

Conjunctival ganglioglioma as a feature of basal cell nevus syndrome

“…Radiation therapy and chemotherapy can be reserved for an unresectable recurrence. 1,2,5 The prevalence of Gorlin syndrome has been estimated at 1/56,000. Manifestations of the nevoid basalcell carcinoma syndrome include multiple basal-cell carcinomata, cysts of the jaws, and skeletal-specifically, rib-abnormalities.…”

Rosette-forming glioneuronal tumour of the fourth ventricle: case report and review of the literature

“…Pilocytic astrocytoma has small round cells as well as astrocytic cells but rosette structures like those of RGNT are not found in PA [17,19]. There is also no evidence of neural differentiation in the rounded cells of pilocytic astrocytoma [3]. Dysembryoplastic neuroepithelial tumour has mature neurons in mucinous pools that help for differentiating from RGNT.…”

“…The main differential diagnosis of RGNT includes pilocytic astrocytoma (PA), dysembryoplastic neuroepithelial tumour, central neurocytoma, plexus papilloma, oligodendroglioma, ependymoma, primitive neuroectodermal tumour (PNET), glioneuronal tumour with neuropil-like islands (rosette) glioneuronal tumour, papillary glioneuronal tumour and metastasis [3,15,19,29]. Pilocytic astrocytoma is the most difficult tumour type for differential diagnosis with RGNT.…”

“…These tumours may show evidence of previous intratumoral haemorrhage on MRI [21,30]. Rosette-forming glioneuronal tumours have two components of both neurocytic and glial areas, but usually the glial component of the tumour predominates [3]. Rosette-forming glioneuronal tumours are low-grade tumours with no histopathological signs of malignancy [1,27].…”