Parapharyngeal space meningioma

Abstract

Parapharyngeal space (PPS) meningiomas are rare extracranial tumors that can mimic more common PPS lesions. We report a case of a 23-year-old female who presented with a painless, progressive neck swelling and intraoral bulge. Imaging revealed a well-defined, homogeneously enhancing mass in the left PPS with encasement of the internal carotid artery, compression of the internal jugular vein, and widening of the hypoglossal canal with adjacent dural enhancement. Core biopsy showed meningothelial whorls and psammoma bodies. Immunohistochemistry was positive for EMA and progesterone receptor, negative for S-100, with a low MIB-1 index, consistent with a WHO Grade I meningioma expressing somatostatin receptors. The tumor was deemed unresectable due to complete vascular encasement, and the patient was treated with peptide receptor radionuclide therapy (PRRT), resulting in tumor regression. This case underscores the importance of including meningioma in the differential diagnosis of PPS masses and highlights PRRT as a viable option in select unresectable, receptor-positive cases.

Keywords: Extracranial meningioma; Parapharyngeal space; Peptide receptor radionuclide therapy; Somatostatin receptor.

Fig. 1

Contrast enhanced CT (A) and T2-weighted MRI sequence (B) shows a well circumscribed lobulated mass in the left poststyloid parapharyngeal space encasing the left internal carotid artery (white arrow) and displacing the left internal jugular vein posteriorly (black arrow). Upon closer inspection, the post-contrast T1-weighted sequence (C) shows the intracranial extent of the mass through the left hypoglossal canal and indenting the left pons (dashed arrow). Axial fused (D) and coronal maximum intensity projections (E) of the subsequent 68Ga-DOTANOC scan, show diffuse intense uptake of the radiotracer within the mass (black star), confirming the diagnosis of a meningioma with positive SSTR2 expression.