Pilocytic Astrocytoma Characteristics and Clinical Outcomes

Pilocytic astrocytoma is a generally benign glial neoplasm classified as WHO grade I, most frequently encountered in children and young adults. These tumours exhibit a biphasic histological pattern, often composed of compact bipolar cells with Rosenthal fibres alongside loosely textured microcystic regions. Radiologically, they commonly present as well circumscribed lesions with cystic and solid components, most often localised in the cerebellum, optic pathway, hypothalamic region or brainstem. At the molecular level, nearly all cases harbour single-pathway alterations in the mitogen-activated protein kinase (MAPK) cascade, most typically involving KIAA1549–BRAF fusion or less frequently BRAF V600E mutation, FGFR1 duplications or NF1 inactivation. Gross total resection remains the mainstay of treatment and is associated with long overall survival exceeding 90 per cent at ten years. Subtotal resections or tumours in eloquent locations may be managed with adjuvant therapies, including targeted inhibitors of the MAPK pathway. Progression-free survival is strongly influenced by the extent of initial resection, patient age and specific molecular alterations. While paediatric cases generally follow a favourable course, adult presentations are rarer and demonstrate higher recurrence rates. Emerging evidence emphasises the need for risk-adapted surveillance and the potential for precision interventions based on molecular subtype.

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Pilocytic Astrocytoma Characteristics and Clinical Outcomes publication trend

The graph below shows the total number of articles in pilocytic astrocytoma characteristics and clinical outcomes across all publications each year (not limited to Nature Index journals).

Technical terms

Pilocytic astrocytoma: A World Health Organization grade I glioma composed of bipolar cells and microcystic areas, predominantly affecting children and young adults.

WHO grade I: The lowest malignancy grade in the World Health Organization classification, indicative of slow growth and favourable prognosis.

MAPK pathway: A signalling cascade (mitogen-activated protein kinase) frequently altered in pilocytic astrocytoma, driving tumour proliferation.

Gross total resection (GTR): Surgical removal of all visible tumour, often correlated with improved long-term outcomes.

Progression-free survival (PFS): The time from initial treatment to documented tumour progression or recurrence.

Overall survival (OS): The duration from diagnosis or treatment initiation until death from any cause.

Cut green pepper sign: A distinct enhancement pattern on post-contrast T1-weighted MRI characterised by a curvilinear rind suggestive of pilocytic astrocytoma in the suprasellar region.

References

1. A novel MRI feature, the cut green pepper sign, can help differentiate a suprasellar pilocytic astrocytoma from an adamantinomatous craniopharyngioma. BMC Medical Imaging (2023).
2. Towards a Risk-Based Follow-Up Surveillance Imaging Schedule for Children and Adolescents with Low-Grade Glioma. Current Oncology (2024).
3. Pilocytic astrocytoma: pathology, molecular mechanisms and markers. Acta Neuropathologica (2015).
4. Clinical characteristics and prognostic factors of adult patients with pilocytic astrocytoma. Journal of Neuro-Oncology (2020).