MICROSCOPIC DESCRIPTION: Sections show a tumour demonstrating histological features of both schwannoma and meningioma. The schwannoma component shows areas composed of short fascicles of tumour cells (Antoni A) with focal nuclear pallisading (Verocay bodies) and loose fibrillary areas (Antoni B). Tumour cells contain bland wavy nuclei with inconspicuous nucleoli.
The meningioma component shows a moderately hypercellular meningioma with a well-developed syncytial architecture. Focal psammomatous calcifications are present. Tumour cells demonstrate uniform nuclear features.
Focal dural attachment and bone invasion is noted. No mitoses, necrosis or brain invasion are seen.
Immunohistochemical results confirm a S100+ schwannoma component andEMA+ meningioma component. The progesterone receptor immunostain is positive within both components.
DIAGNOSIS: Collision tumour (schwannoma and meningioma WHO grade I).