Tongue cancer

Anatomy of the Pharyngeal Mucosal Space

The unified pharyngeal mucosal space (Pharyngeal mucosal space - PMS) is topographically and functionally divided into two major sections: the nasopharynx and the oropharynx. Understanding these boundaries is critical for determining the location of the primary tumor and its routes of spread.

The oropharynx (Oropharynx) has the following anatomical landmarks:

• Anterior boundary: the base of the tongue and the valleculae. It is the valleculae that serve as the lower dividing line between the oropharynx and the laryngopharynx. A crucial anatomical postulate states that the base of the tongue is a rightful part of the oropharynx, not the oral cavity.
• Lateral boundaries: the palatine tonsils (faucial tonsils) and the glossotonsillar sulcus.
• Superior boundary: the structures of the soft palate, which physically separate the oropharynx from the overlying nasopharynx.
• Posterior boundary: the posterior pharyngeal wall.

Superior to the oropharynx lies the nasopharynx (Nasopharynx), which is bounded superiorly by the skull base, posteriorly by the anterior arch of the first cervical vertebra (C1), and anteriorly by the choanae. On its lateral wall, the torus tubarius and the pharyngeal recess (Rosenmüller's fossa) are distinguished.

Malignant Neoplasms of the Oropharynx and Base of the Tongue

If a patient is diagnosed with a malignant process in the oropharynx (including the base of the tongue), it is almost always squamous cell carcinoma (SCC) morphologically.

The tumor is most often localized in the region of the palatine tonsil and the anterior faucial pillar; however, the lingual tonsil, which forms the basis of the base of the tongue, is also a zone at risk. The anterior faucial pillar, which covers the palatoglossus muscle, often acts as a kind of anatomical "conduit" through which malignant cells spread cranially (upward).

Unlike the oropharynx, the nasopharynx is dominated by nasopharyngeal carcinoma (NPC), which is subdivided into keratinizing, non-keratinizing, and undifferentiated types. This tumor is strongly associated with Epstein-Barr virus (EBV) infection, the titers of which physicians use as a specific tumor marker.

Principles of diagnostic imaging

To assess the extent of tumors in the pharyngeal mucosal space, MRI is the preferred method. Magnetic resonance imaging is significantly superior to CT in visualizing soft tissue structures, which is critical for planning intensity-modulated radiation therapy (IMRT) or proton therapy.

On MRI scans (T2-weighted images), radiologists can clearly trace tumor invasion. For example, the pharyngobasilar fascia on axial slices has an "inverted crown" shape. It acts as a barrier separating the lymphoid tissue from the parapharyngeal (laterally) and retropharyngeal (posteriorly) spaces. With aggressive growth, the malignant tumor destroys these barriers, infiltrating adjacent fascial spaces.

In addition to tumors, visualization of the oropharynx often requires differential diagnosis with acute inflammatory processes, such as a peritonsillar abscess. In such cases, contrast-enhanced CT (CECT) is preferred. The scans reveal an enlarged tonsil with a hypodense center and characteristic peripheral ring enhancement. If the inflammation spreads to the masticator space, the patient clinically manifests trismus.

Class and exam questions

What else to study on this topic

• Routes of Intracranial and Perineural Spread of Nasopharyngeal Carcinoma
• Specifics of Nasopharyngeal Carcinoma Metastasis (Lymphogenous and Hematogenous Metastases)
• Benign Lesions of the Nasopharynx: Adenoid Hypertrophy and Thornwaldt Cyst
• Mechanisms of Formation and Complications of Peritonsillar Abscesses
• The Role of Epstein-Barr Virus (EBV) in the Development of Nasopharyngeal Carcinoma

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Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.