Polymorphous Low-Grade Neuroepithelial Tumor of the Young (PLNTY): A Rare Entity

Area of Science:

• Pediatric neuro-oncology
• Molecular diagnostics
• Central nervous system (CNS) tumor classification

Background:

• Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a rare CNS tumor.
• Diagnosis can be challenging due to overlapping features with other low-grade gliomas.
• Molecular profiling is increasingly important for accurate classification.

Purpose of the Study:

• To report a case of PLNTY with an unusual immunohistochemical profile.
• To highlight the diagnostic utility of next-generation sequencing (NGS) in identifying specific molecular alterations.
• To emphasize the impact of molecular findings on pediatric CNS tumor diagnosis and care.

Main Methods:

• A case study of an 11-year-old female presenting with a seizure and a temporal lobe mass.
• Histopathological examination including immunohistochemistry (IHC) for various markers (Synaptophysin, NeuN, CD34, p16, SOX10, GFAP, p53, ATRX, Ki67).
• Next-generation sequencing (NGS) to detect genetic alterations, including gene fusions.

Main Results:

• The tumor exhibited an unusual IHC profile with diffuse synaptophysin positivity and negativity for NeuN.
• Key findings included patchy CD34 and p16 positivity, rare SOX10 and GFAP, strong p53 positivity in 20% of cells, retained ATRX, and a 3% Ki67 index.
• NGS revealed a specific FGFR2::SHTN1 gene fusion.

Conclusions:

• This case underscores the diagnostic value of NGS in identifying specific molecular drivers in CNS tumors.
• Accurate molecular classification, such as identifying the FGFR2::SHTN1 fusion, is essential for diagnosing rare entities like PLNTY.
• Advances in molecular testing significantly impact the diagnosis and management of pediatric CNS tumors.