A large T1 hypointense and T2 hyperintense circumscribed mass with diffuse vivid enhancement measures 6.1 x 5.4 x 2.6 cm ( craniocaudal by transverse by AP ). The mass is indistinguishable laterally from the deep lobe of the parotid, displaces the carotid arteries posteriorly, the parapharyngeal fat medially and anteromedially, and the medial and lateral pterygoid muscles anteriorly. The inferior portion of the mass inferiorly displaces the submandibular gland.
The inner surface of the left mandibular ramus and angle is abutted but not invaded or destroyed.
Mass-effect from this lesion also causes severe effacement of the oropharynx and nasopharynx and obstructs the left eustachian tube with mastoid effusion.
No perineural thickening or enhancement along the inferior alveoli, mandibular or facial nerve is identified. No cervical lymph node enlargement.
Conclusion: The pattern of structure displacement suggests this is a mass arising from the deep lobe of the parotid, most likely a large pleomorphic adenoma. A possible alternate diagnosis would be a schwannoma at the anterior aspect of the carotid sheath.