Answer: Meningioma

Histology: The subepithelium is infiltrated by whorls of spindled to ovoid epithelioid cells with eosinophilic cytoplasm and oval nuclei. The tumor cells are immunoreactive for EMA and progesterone receptor, but not for CD34, actin or FXIIIa

Discussion: Meningioma of the nasal cavity may either represent a primary extracranial meningioma or an intracranial tumor with extracranial extension. Most represent true extracranial tumors, but correlation with the clinical and radiographic findings is necessary to make the distinction. The nasal meningiomas retain the histopathologic features of their intracranial counterparts including morphologic variability as a function of histologic subtypes (e.g. fibroblastic, meningotheliomatous, psammomatous). Accordingly, they are usually easy to diagnose provided that they are included in the differential diagnosis of intranasal masses. If there is any uncertainty, immunohistochemistry can be used to confirm the diagnosis. Nasal meningiomas are typically immunoreactive for EMA and non-immunoreactive for cytokeratin, S100, CD34 or FXIIIa. The extent of surgery for the removal of nasal meningiomas depends on the size of the tumor and the presence of any intracranial component.