Pharyngeal Mucosal Space Overview

Summary Thoughts: Pharyngeal Mucosal Space

Clinically, the upper aerodigestive track is often divided into the naso-, oro-, and hypopharyngeal subsites. Each of these subsites is unified, however, with mucosa that is subject to shared pathology. The pharyngeal mucosal space (PMS) is a key suprahyoid neck (SHN) space that represents the pharyngeal surfac e. The PMS has on its non-airway surface the middle layer of deep cervical fascia (ML-DCF). Important PMS contents include the mucosal surface of the pharynx, pharyngeal lymphatic ring (adenoidal, palatine, and lingual tonsils), and submucosal minor salivary glands.

An enlarging PMS mass of the palatine tonsil or nasopharyngeal lateral pharyngeal recess displaces the parapharyngeal space (PPS) fat laterally. Disruption of the mucosal and submucosal landmarks also occurs in PMS masses.

Important PMS malignancies include squamous cell carcinoma (SCCa) arising from the mucosal surface, non-Hodgkin lymphoma (NHL) from the pharyngeal lymphatic ring, and minor salivary gland carcinoma from the normal submucosal minor salivary glands. Of these, SCCa is by far the most frequent. Staging of SCCa primary and nodal disease is one of the most common reasons for imaging studies in the head and neck.

The PMS is not a true space as it is not enclosed on all sides by fascia. It is an imaging construct to overcome the problems encountered in describing a lesion of the pharynx as nasopharyngeal, oropharyngeal, and hypopharyngeal. These terms, although universally applied to lesions of the pharyngeal surface, do not address the deep tissue component of an invasive PMS mass. Describing a lesion as primary to the PMS with extension into the adjacent SHN spaces clearly delineates lesion extent in a radiologic report.