Surgical resection was performed.
MICROSCOPIC DESCRIPTION:
Paraffin sections show a moderately cellular tumour with a dural attachment and enclosing fasciculi of myelinated nerve fibres. Tumour cells have uniform round and oval nuclei with vesicular chromatin and a moderate amount of clear, glycogen rich cytoplasm. These are arranged predominantly in solid sheets and lobules.
A vague syncytial arrangement of tumour cells is descernible in several areas. Scattered mitotic figures are identified (2 in 20 HPF).
No areas of necrosis are seen.
Immunohistochemistry shows strong membrane staining in tumour cells for somatostatin receptor 2 (SSR2) and strong nuclear staining for progesterone receptor (PgR). There is strong staining for S-100 protein in incorporated nerve bundles but tumour cells are S-100 negative. No staining for GFAP, cytokeratin CAM5.2, synaptophysin, chromogranin or oestrogen receptor (ER) is seen in tumour cells.
The features are of clear cell meningioma (WHO Grade II).
DIAGNOSIS:
Clear cell meningioma (WHO Grade II).