High-grade astrocytoma with piloid features

Last revised by Assoc Prof Frank Gaillard on 26 Nov 2021

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

This rare tumor was first included in the 5th Edition (2021) of the WHO classification of CNS tumors as a circumscribed astrocytic glioma 2

It is defined by a characteristic DNS 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

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

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