Juvenile pilocytic astrocytomas do not undergo spontaneous malignant transformation: Grounds for designation as a hamartoma
- Published Online First 25 October 2007
Aim: To determine whether juvenile pilocytic astrocytomas WHO grade I have the potential for spontaneous malignant transformation.
Methods: A literature search was performed cross-referencing juvenile pilocytic astrocytoma, pilocytic astrocytoma, astrocytoma grade I, optic glioma, glioma, low-grade gliomas and malignant transformation, anaplasia or anaplastic change. Bibliographic PubMed and Google searches were performed, and reference ophthalmology and neuropathology textbooks were utilised.
Results: A total of 49 purported cases of malignant transformation were found. Twenty of these tumours, however, did not initially match criteria for juvenile pilocytic astrocytoma WHO grade I and were excluded. Six other cases were located within the irradiated field but represented anaplasias developing independently of the primary tumour. The remaining 24 malignancies had all been previously irradiated.
Conclusion: Juvenile pilocytic astrocytomas WHO grade I do not undergo spontaneous anaplastic transformation. Malignant transformations have only been demonstrated following radiation therapy. Earlier clinical and histopathological opinions regarding juvenile pilocytic astrocytomas as hamartomatous lesions are reaffirmed.