High-grade astrocytoma with piloid features
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At the time the article was created Frank Gaillard had no recorded disclosures.View Frank Gaillard's current disclosures
At the time the article was last revised Ashesh Ishwarlal Ranchod had no financial relationships to ineligible companies to disclose.View Ashesh Ishwarlal Ranchod's current disclosures
High-grade astrocytoma with piloid features is a recently described rare tumor most commonly encountered in the posterior fossa of adults, especially those with neurofibromatosis type 1. It appears heterogeneous and has a dismal prognosis.
Due to the small number of patients so far reported, it is difficult to make strong pronouncements on the epidemiology of this tumor, however, cases so far appear to be primarily in middle-aged and elderly individuals 1,3. Neurofibromatosis type 1 appears to be an association 1.
It is defined by a characteristic DNA-methylation profile.
The small number of tumors reported have occurred throughout the brain, brainstem and spinal cord with a predilection for the posterior fossa, and especially the cerebellum 1.
The histological appearance of these tumors is varied with reported cases having histological diagnoses of anaplastic pilocytic astrocytoma or glioblastoma 1.
Alterations are commonly encountered in 1:
Due to the small number of cases reported to date, specific or even suggestive imaging features are not yet evident especially as the tumors that have been described are heterogeneous in location (see above) and appearance 1.
Generally, they appear to be peripherally enhancing lesions with high T2 signal but without diffusion restriction of either central or peripheral components 1.
Treatment and prognosis
No tumor specific treatments are available at this time with treatment being empirical consisting of maximal safe surgical resection with concurrent chemoradiotherapy (e.g. temozolomide) 1.
Prognosis is poor, similar to glioblastoma (IDH-wildtype) 1.
- 1. Bender K, Perez E, Chirica M et al. High-Grade Astrocytoma with Piloid Features (HGAP): The Charité Experience with a New Central Nervous System Tumor Entity. J Neurooncol. 2021;153(1):109-20. doi:10.1007/s11060-021-03749-z - Pubmed
- 2. Louis D, Perry A, Wesseling P et al. The 2021 WHO Classification of Tumors of the Central Nervous System: A Summary. Neuro-Oncology. 2021;23(8):1231-51. doi:10.1093/neuonc/noab106 - Pubmed
- 3. Biczok A, Strübing F, Eder J et al. Molecular Diagnostics Helps to Identify Distinct Subgroups of Spinal Astrocytomas. Acta Neuropathol Commun. 2021;9(1):119. doi:10.1186/s40478-021-01222-6 - Pubmed