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Pediatric-type diffuse low grade gliomas: Histomolecular profile and practical approach to their integrated diagnosis
Suvendu Purkait1, Swati Mahajan2, Mehar C Sharma2
1Department of Pathology and Lab Medicine, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India.
Insights
Pediatric diffuse low-grade gliomas (pDLGG) are rare CNS tumors with unique characteristics. Understanding their distinct molecular profiles is crucial for targeted therapy and improved clinical outcomes in children.
Area of Science:
- Pediatric neuro-oncology
- Central nervous system (CNS) neoplasms
- Molecular neuropathology
Background:
- Low-grade gliomas are common primary CNS tumors in children, with diffuse variants (pDLGG) being rare but distinct from adult counterparts.
- The 5th edition WHO CNS classification identifies four pDLGG histomolecular entities: MYB/MYBL1-altered diffuse astrocytoma, angiocentric glioma, PLNTY, and MAPK pathway-altered diffuse low-grade glioma.
- While molecular profiles correlate with morphology, they are not entirely specific, highlighting the need for precise molecular diagnostics.
Purpose of the Study:
- To review the distinct biological behavior, molecular profiles, and clinical outcomes of pediatric diffuse low-grade gliomas (pDLGG).
- To outline the four histomolecular entities of pDLGG according to the latest WHO CNS classification.
- To emphasize the therapeutic implications of molecular alterations in pDLGG and the availability of targeted therapies.
Main Methods:
- Review of current literature on pediatric diffuse low-grade gliomas.
- Analysis of the 5th edition WHO CNS classification for pDLGG subtyping.
- Discussion of molecular testing platforms and their clinical relevance.
Main Results:
- pDLGG exhibit unique molecular features differentiating them from adult low-grade gliomas.
- Four distinct histomolecular subtypes of pDLGG are recognized, each with specific molecular alterations.
- Molecular alterations in pDLGG offer targets for novel, personalized therapies.
Conclusions:
- Accurate histomolecular classification of pDLGG is essential for guiding treatment strategies.
- Targeted therapies based on identified molecular alterations hold significant promise for improving outcomes in pediatric patients.
- Standardized molecular testing is crucial for routine clinical assessment, despite the lack of a universally recommended method by WHO.
Abstract:
Low-grade gliomas are the most common primary central nervous system (CNS) neoplasms in the pediatric age group. The majority of these tumors are circumscribed, while diffuse low-grade gliomas are relatively rare. The pediatric type diffuse low-grade gliomas (pDLGG) have a distinctly different biological behavior, molecular profile, and clinical outcome as compared to their adult counterpart. In the 5th edition of World Health Organization (WHO) CNS classification, pDLGGs are subclassified into four distinct histomolecular entities, namely, (i) diffuse astrocytoma, MYB- or MYBL1-altered, (ii) angiocentric glioma, (iii) polymorphous low-grade neuroepithelial tumor of the young (PLNTY), and (iv) diffuse low-grade glioma, MAPK pathway-altered. Although the molecular profile, to a great extent, aligns with the morphological features, it is not specific. Many of the molecular alterations described in pDLGG have therapeutic implications with the availability of newer targeted therapies. A wide range of testing platforms are available for routine assessment of these molecular alterations in clinical laboratories, though WHO does not recommend any particular method.
