Abstract

Aim: Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a rare entity with a diffuse, infiltrative pattern, awaiting to be included in the WHO CNS tumor classification; it occurs in pediatric and young patients with seizures and harbors mutually exclusive BRAFV600E or FGFR mutations. Nonetheless, the presence of these mutations may not be obligatory for diagnosis. The conventional histology of these tumors resembles that of oligodendrogliomas. We aimed to discuss a PLNTY case in a young woman presenting with seizures due to a parietal brain tumor and to provide an analysis of the literature. Histopathologically the tumor was consistent of oligodendroglioma-like neoplastic cells showing almost diffuse CD34 and olig-2 staining, retained ATRX expression, p53-negativity, and a low Ki67 index with no necrosis or microvascular proliferation.
Materials and methods: 1p/19q statuswas analyzed with FISH; IDH1 and IDH2 mutations were analyzed with minisequence analysis. Translocations, mutations, and expression analyses were studied for 18, 19, and 21 genes via targeted new-generation deep RNA sequencing, respectively.
Results: The tumor did not carry 1p/19q codeletion, was IDH wild-type, and had radiological features compatible with the diagnosis of PLNTY. The tumor did not show BRAF or FGFR alterations but had an EGFR c.2342A>G (p.Asn781Ser) mutation which was likely a non-driver mutation due to its low allele frequency of 4%.
Conclusion: PLNTYs are rare brain tumors, and their accurate diagnosis is important to avoid improper management. Their prognosis shall be stratified according to their mutations.

Author Details

Authors

• Ayca Ersen Danyeli¹
• Meric A. Altinoz²
• Ramazan Sari³
• Ilhan Elmaci^{3, 4}

Departments

• ¹ Department of Pathology,
• ² Department of Medical Biochemistry, Acibadem Mehmet Ali Aydinlar University, School of Medicine,
• ³ Department of Neurosurgery, Acibadem Maslak Hospital, and
• ⁴ Department of Neurosurgery, Acibadem Mehmet Ali Aydinlar University, School of Medicine, Istanbul, Turkey

Address

İlhan Elmaci, MD, Professor
Department of Neurosurgery
Acibadem Mehmet Ali Aydinlar University
School of Medicine
Istanbul, Turkey
Email: [email protected]

Citation