The patient went on to have surgery.
The sections show a moderately cellular astrocytic tumour. Some of the astrocytes contain elongated, angulated and hyperchromatic nuclei. Others show protoplasmic form with rounder nuclei in a loose background. Scattered mitoses are seen. Some of the blood vessels appear hyalinised but there is no evidence of endothelial cell hyperplasia. Small numbers of tumour cells extend into the overlying cortex. No evidence of necrosis is seen. The Ki-67 index is 5-6%.
Final Diagnosis: The features are those of an anaplastic astrocytoma (WHO grade III)