Circumscribed Pilocytic Astrocytoma Including Pilomyxoid and Intermediate Pilomyxoid Variants - A Single...

Area of Science:

• Pediatric neuro-oncology
• Tumor pathology
• Cancer research

Background:

• Classical pilocytic astrocytoma (PA) is a common childhood WHO Grade I glioma, with a subtype, pilomyxoid astrocytoma (PMA), initially considered more aggressive.
• The 2021 WHO classification omits a grade for PMA due to limited data, prompting further investigation into its characteristics.

Purpose of the Study:

• To compare the clinico-radiological behavior, histomorphology, and outcomes of pilocytic astrocytoma (PA) and pilomyxoid astrocytoma (PMA).
• To evaluate the current evidence for grading pilomyxoid astrocytoma (PMA).

Main Methods:

• Retrospective analysis of 14 PA, 4 PMA, and 2 intermediate pilomyxoid tumor (IPMT) cases.
• Comparison of patient demographics, tumor location, size, imaging features, surgical resection extent, and follow-up data.
• Histopathological and immunomarker analysis.

Main Results:

• Majority of patients were pediatric (PA 78%, PMA 100%), with the cerebellum being the commonest location for both tumor types.
• Tumor dimensions and solid-cystic features showed overlap between PA and PMA; gross total resection was achieved in 78% of PA and 75% of PMA.
• Follow-up revealed recurrence in 2 PA cases and one PA death, with no significant differences in clinico-radiological behavior or outcomes observed between PA and PMA.

Conclusions:

• Pilocytic astrocytoma (PA) and pilomyxoid astrocytoma (PMA) exhibit considerable overlap in clinico-radiological presentation, surgical outcomes, and immunophenotype.
• Current data do not substantiate classifying pilomyxoid astrocytoma (PMA) as a higher-grade tumor.
• Further multidisciplinary studies are required to definitively characterize PMA and establish its precise classification.