Parapharyngeal Mass

Marci J. Neidich and David L. Steward

History

A 55-year-old woman with a history of three surgical resections for right recurrent pleomorphic adenoma is referred for evaluation of a neck mass. She originally had a parotid mass at the age of 25; this mass was resected, with pathology revealing pleomorphic adenoma. This recurred 1 year later, and a completion parotidectomy was performed. She had a long disease-free interval until 10 years ago, when she had another resection of mass in the parotid bed. She now has 4 months of an enlarging right neck mass, intermittent hoarseness, and right-sided otalgia. She has also noticed some mild dysphagia to solids over the past several weeks but no odynophagia. She has a history of tonsillectomy as a young child. She drinks no alcohol, has never smoked, and has no other symptoms or significant medical history.

Examination reveals a thin woman (body mass index 20) breathing quietly. She has a palpable right-sided level II mass on palpation of the neck. Intraoral examination reveals postsurgical absence of the tonsils and mild fullness of the right oropharyngeal wall. There is no erythema or exudate of the oropharynx. She is afebrile and has mild trismus. Ear examination is normal. On the right, she has an obvious facial droop at rest with incomplete eye closure consistent with a House-Brackman IV/VI. Otherwise, cranial nerves are grossly intact.

Differential Diagnosis—Key Points

1. Critical to the understanding of the diagnosis and management of these masses is knowledge of the anatomy and boundaries of the parapharyngeal space. The space is divided into two compartments through which various structures course. The anterolateral prestyloid space contains mostly fat, a variable portion of the deep lobe of the parotid, internal maxillary artery, inferior alveolar nerve, lingual nerve, and the auriculotemporal nerve. The posteromedial retrostyloid space contains the carotid, jugular vein, cranial nerves IX–XII, sympathetic chain, and lymph nodes. This knowledge will help narrow down the diagnosis once imaging delineates the location of the mass.

2. The differential diagnosis of masses that arise in this space is vast, with many case reports existing in the literature of rare presentations of various tumors. The most common diagnoses are presented below:

B. Neurogenic tumors (20–25%): This includes schwannoma, neurofibroma, glomus vagale, carotid body tumor.

C. Lymph node (15%): Lymph node enlargement may be primary (i.e., lymphoma) or metastatic disease from a pharyngeal cancer at any level.

D. One must keep in mind a variety of other miscellaneous tumors: these may be arising from muscle (rhabdomyoma, leiomyoma), connective tissue (lipoma, fibroma), or congenital (branchial cleft cyst, dermoid, lymphangioma). Another possibility is that of pseudotumors such as aneurysm, abscess, and myositis.