Papillary Glioneuronal Tumor: Radiological Evidence of a Newly Established Tumor Entity

Mixed neuronal-glial tumors are rare and challenging to subclassify. One recently recognized variant, papillary glioneuronal tumor (PGNT), is characterized by prominent pseudopapillary structures and glioneuronal elements. We identified a novel translocation, t(9;17)(q31;q24), as the sole karyotypic anomaly in two PGNTs. A fluorescence in situ hybridization (FISH)-based positional cloning strategy revealed SLC44A1, a member of the choline transporter-like protein family, and PRKCA, a protein kinase C family member of serine/threonine-specific protein kinases, as the 9q31 and 17q24 breakpoint candidate genes, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) analysis using a forward primer from SLC44A1 exon 5 and a reverse primer from PRKCA exon 10 confirmed the presence of a SLC44A1-PRKCA fusion product in both tumors. Sequencing of each chimeric transcript uncovered an identical fusion cDNA junction occurring between SLC44A1 exon 15 and PRKCA exon 9. A dual-color breakpoint-spanning probe set custom-designed for interphase cell recognition of the translocation event identified the fusion in a third PGNT. These results suggest that the t(9;17)(q31;q24) with the resultant novel fusion oncogene SLC44A1-PRKCA is the defining molecular feature of PGNT that may be responsible for its pathogenesis. The FISH and RT-PCR assays developed in this study can serve as valuable diagnostic adjuncts for this rare disease entity.

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“…ring-like contrast enhancement (23,28). PGNT is generally considered a low-grade neoplasm because of its indolent clinical course.…”

Section: Discussionmentioning

confidence: 99%

Identification of a Novel, Recurrent SLC44A1‐PRKCA Fusion in Papillary Glioneuronal Tumor

Bridge¹,

Liu

Sümegi

et al. 2012

Brain Pathology

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“…Histopathological features, including biphasic components of glial and neuronal pattern as well as radiological characteristics such as frequent occurrence of a cystic lesion with mural nodule (39%, Table 3) or mixed solid-cystic lesions (39%, Table 3) with ring-like enhancement in MRI, are able to facilitate the diagnosis [9], [50]. However, the differentiation among ganglioglioma, pleomorphic xanthoastrocytoma, pilocytic astrocytoma and dysembryoplastic neuroepithelial tumor can sometimes be challenging [7], [39], [49].…”

Section: Discussionmentioning

confidence: 99%

An Individual Patient Data Meta-Analysis on Characteristics and Outcome of Patients with Papillary Glioneuronal Tumor, Rosette Glioneuronal Tumor with Neuropil-Like Islands and Rosette Forming Glioneuronal Tumor of the Fourth Ventricle

et al. 2014

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Background and PurposeIn 2007, the WHO classification of brain tumors was extended by three new entities of glioneuronal tumors: papillary glioneuronal tumor (PGNT), rosette-forming glioneuronal tumor of the fourth ventricle (RGNT) and glioneuronal tumor with neuropil-like islands (GNTNI). Focusing on clinical characteristics and outcome, the authors performed a comprehensive individual patient data (IPD) meta-analysis of the cases reported in literature until December 2012.MethodsPubMed, Embase and Web of Science were searched for peer-reviewed articles reporting on PGNT, RGNT, and GNTNI using predefined keywords.Results95 publications reported on 182 patients (PGNT, 71; GNTNI, 26; RGNT, 85). Median age at diagnosis was 23 years (range 4–75) for PGNT, 27 years (range 6–79) for RGNT, and 40 years (range 2–65) for GNTNI. Ninety-seven percent of PGNT and 69% of GNTNI were located in the supratentorial region, 23% of GNTNI were in the spinal cord, and 80% of RGNT were localized in the posterior fossa. Complete resection was reported in 52 PGNT (73%), 36 RGNT (42%), and 7 GNTNI (27%) patients. Eight PGNT, 3 RGNT, and 12 GNTNI patients were treated with chemo- and/or radiotherapy as the primary postoperative treatment. Follow-up data were available for 132 cases. After a median follow-up time of 1.5 years (range 0.2–25) across all patients, 1.5-year progression-free survival rates were 52±12% for GNTNI, 86±5% for PGNT, and 100% for RGNT. The 1.5-year overall-survival were 95±5%, 98±2%, and 100%, respectively.ConclusionsThe clinical understanding of the three new entities of glioneuronal tumors, PGNT, RGNT and GNTNI, is currently emerging. The present meta-analysis will hopefully contribute to a delineation of their diagnostic, therapeutic, and prognostic profiles. However, the available data do not provide a solid basis to define the optimum treatment approach. Hence, a central register should be established.

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“…One case was in close proximity to the lateral ventricle, a feature that was previously reported. 3 Histologically, the lesion is distinctive for its biphasic architecture, pseudopapillary pattern, and lack of anaplastic features. The observed degenerative changes were previously reported with variable frequencies.…”

Section: Discussionmentioning

confidence: 99%