A Rare Case of Paranasal Sinus Schwannoma with Intracranial Extension

Abstract

Paranasal sinus schwannomas are uncommon and account for less than 4% of head and neck schwannomas. Intracranial extension and aggressive behaviour are very rarely observed in these tumours leading to misdiagnosis of a malignant neoplasm. Here, we report a case of a 35-year-old male with complaint of proptosis. MRI showed a tumour in the region of ethmoid sinus with expansion into anterior cranial fossa. Microscopy revealed a biphasic tumour with compact and loose areas. Tumour was composed of spindle cells with wavy nuclei, showing focal palisading and a strong immunoreactivity for S100. MIB-1 index was around 1%. A diagnosis of Schwannoma was favoured based on histology and immunohistochemistry.

Keywords

• s100
• antoni a
• antoni b
• middle cranial fossa