Nasopharynx: Clinical, pathologic, and radiologic assessment
Section snippets
Anatomy
The pharynx is subdivided into the nasopharynx, oropharynx, and hypopharynx (Fig. 1) [15], [16]. The nasopharynx is a tubular structure extending from the base of the skull, principally the clivus and floor of the sphenoid sinus, inferiorly to the level of the junction of the hard and soft palates. The anterior border is formed by the choanal area and the posterior bony septum representing the vomer. The posterior border is composed of the clivus and the upper two cervical vertebrae and the
Clinical findings and evaluation
The presenting finding of carcinoma of the nasopharynx is usually secondary to a metastatic neck mass, which occurs in approximately 60% to 85% of patients [17], [18]. NPC is solely confined to the nasopharynx without lymph node metastases in only 9% of patients [11], [19]. Systemic dissemination occurs more commonly in NPC when compared with other head and neck cancers [20]. Distant metastases occur in 5% to 10% of patients at initial presentation; bone, including bone marrow [21], [22],
Histopathology of malignant tumors of the nasopharynx
Most head and neck cancers are SCCs (90%). The nasopharynx is the site of various histopathologic malignant tumors that cannot be differentiated by radiologic methods, however (Box 1) [49], [50]. The predominant histopathologic type is represented by the various carcinomas, chiefly the nonkeratinizing undifferentiated carcinoma. Although SCC is by far the most common type of mucosal malignancy in the head and neck area, it is the rarest type of NPC [30]. The undifferentiated carcinoma is the
Radiologic techniques
Radiologic evaluation of the nasopharynx is essential in the assessment of this group of diverse malignant lesions [13], [14], [34], [69], [70], [71]. CT conventional films in the lateral and base projection previously were used but are now only indicated in pediatric patients for assessment of enlarged adenoid tissue. Smaller lesions, especially if they arise from the lateral wall of the nasopharynx, or tumors with minimal bone destruction, are readily missed on conventional films. CT and MR
Nasopharyngeal carcinoma
Carcinoma of the nasopharynx manifests various patterns that are optimally evaluated by CT and MR imaging [13], [72]. The findings become an integral part in staging of NPCs (Box 2) [14], [70], [80]. The imaging manifestations of NPCs are variable; this articleattempts to illustrate and describe the various patterns encountered in this disease [9], [70], [72], [81].
The diagnosis of carcinoma is strongly suggested when a mass is demonstrated in the nasopharynx, with associated bone destruction,
Parapharyngeal tumors
Several benign and malignant tumors in the PPS can mimic a primary malignant tumor of the nasopharynx [106]. These lesions arise laterally from the deep lobe of the parotid gland or from minor salivary glands in the pharyngeal mucosa. Parapharyngeal tumors, benign or malignant, arise from the deep portion of the parotid gland or minor salivary glands in the PPS and encroach on the lateral part of the nasopharynx. Among the benign tumors, pleomorphic adenoma and schwannoma should be considered
Summary
NPC represents 0.2% of malignant disease in the white population but is more common in southern China, among Chinese in East Asia and the United States, and in North Africa, including Saudi Arabia. NPC in these ethnic groups tends to manifest at a younger age. Undifferentiated carcinoma is the most common histopathologic type and is associated with EBV. The tumor is optimally assessed with CT and MR imaging for staging; PET scanning provides optimal assessment of recurrent tumor or small lymph
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