Conversion of a Gemistocytic Astrocytoma to a Fibrillary Astrocytoma after Temozolomide and Radiation Therapy

In most instances, gemistocytic astrocytoma progresses to anaplastic astrocytoma at the time of recurrence. Here, we report an unusual case where a gemistocytic astrocytoma converted to a more benign fibrillary histology after temozolomide/radiation therapy. We present the case of a 26-year-old woman with a history of fibrillary astrocytoma that was followed over a span of eight years and underwent three craniotomies. The pathology from the first craniotomy revealed a fibrillary astrocytoma. The pathology from the second craniotomy (one year after the first resection) revealed findings consistent with a gemistocytic astrocytoma. The pathology from a third craniotomy (seven years after the second resection) revealed a fibrillary astrocytoma without a significant gemistocytic component. This is the first documented case of a gemistocytic astrocytoma converting to a more benign fibrillary pathology at the time of recurrence. We speculate that the phenomenon is the result of the inherently heterogeneous astrocytic subpopulations that were differentially sensitive to chemo/radiation. Categories: Neurology, Neurosurgery, Oncology