Spontaneous Anaplastic Transformation in Cerebellar Pilocytic Astrocytoma: A Case Report and Review Of Literature

Pilocytic atrocytoma(PA) is a World health organization (WHO) grade I astrocytoma. It most commonly develops during first two decades of life with predilection for infratentorial region. The tumor shows a favorable behavior and patients usually have excellent long term improvement. Histologic progression and features of anaplasia is a rare event in pilocytic astrocytomas and is commonly seen with the history of radiation and is associated with aggressive behavior. Malignant or anaplastic pilocytic transformation has only been mentioned in the WHO classification of CNS tumors, however it has not been assigned a grade. Nevertheless, the literature has a number of case reports and few series which describes definite anaplastic transformation in PAs. We herein report a rare case of progression of anaplasia within 11months of primary diagnosis without antecedent radiotherapy.