Congenital anaplastic astrocytoma differentiated into pilocytic astrocytoma: An autopsy case

Abstract

We report an autopsy case of congenital astrocytoma and its histopathological changes during 5 years of the patient's development from birth to death. At birth, a right exophthalmic tumor was observed, and MRI revealed that the tumor occupied the right orbital space and had also affected the suprasellar diencephalic structures. The right orbital tumor, which was enucleated at 2 months of age, was a highly cellular tumor with moderate pleomorphism resembling anaplastic astrocytoma. On the other hand, at autopsy, a brain tumor was found in the right diencephalic region with features of pilocytic astrocytoma, accompanied by leptomeningeal dissemination. A biopsy specimen, which was obtained from the chiasmatic part of the tumor at 4 months of age, showed an intermediate appearance between the orbital tumor and the brain tumor obtained at autopsy. Immunohistochemical examination confirmed that all three phases of the tumors showed an astrocytic lineage, and the Ki-67 labeling index decreased rapidly after 2 months of age. We believe that this congenital anaplastic astrocytoma differentiated into a pilocytic astrocytoma during the 5 years of the patient's development. The transformation of the congenital astrocytoma from anaplastic to pilocytic forms can be attributed to the nature of the tumor, namely postmitotic neoplastic cells are characterized by their ability to undergo self-differentiation, along with the organotropism of the developing brain.