The Nasopharynx - nasopharyngeal carcinoma

Presentation and Staging

In the United States, nasopharyngeal carcinoma (NPC) accounts for 2% of all HNSCCs. Its unusual epidemiologic and natural history features include a remarkable tendency toward early regional and distant dissemination. NPC also is extremely sensitive to radiotherapy and cytotoxic chemotherapy.

In the adult, the nasopharynx is a chamber that is approximately cuboidal in shape and 4 cm on an edge. It is bounded anteriorly by the choana of the nasal cavity, superiorly by the clivus, and inferiorly by the soft palate. Its posterior wall is the mucosa that overlies the superior constrictor muscles of the pharynx and the C1 and C2 vertebral bodies. The lateral walls contain the Eustachian tube orifices.

The epithelium of the superior lateral walls contains pseudostratified columnar cells and occasional goblet cells while the inferior lateral and posterior walls are stratified squamous in nature. The region is richly endowed with lymphatics that drain to the retropharyngeal and deep cervical nodes.

Malignant neoplasms of the nasopharynx are primarily epithelial, with the presence of keratin associated with a poorer prognosis. The World Health Organization (WHO) recognizes three histopathologic types of NPC: type 1, differentiated SCC (of varying degrees); type 2, nonkeratinizing carcinoma; and type 3, undifferentiated or lymphoepithelial carcinoma. Mixed patterns are common. About 75% of nasopharyngeal carcinomas are type 1 or 2 (or predominantly one or both of these types). The term "lymphoepithelial carcinoma" (type 3) is used when numerous infiltrating lymphocytes are seen.

About one-third of patients present with a neck mass without other complaints, and about 70% to 75% of patients have enlarged neck nodes at presentation. Other common complaints are epistaxis, nasal stuffiness, headache, or hearing loss (generally unilateral). The tumor can spread laterally and superiorly to cause bony destruction of the base of the skull. Frequently, there are cranial nerve findings, with the sixth nerve being most commonly involved. There are two principal cranial nerve syndromes associated with NPC: (1) the retroparotidian syndrome, involving cranial nerves IX, X, XI, and XII, and (2) the petrosphenoidal syndrome, involving cranial nerves III, IV, V, and VI (and occasionally cranial nerve II via extension through the foramen lacerum into the middle cranial fossa). Evaluation of the nasopharynx should consist of direct visualization with a fiberoptic scope. A CT and/or MRI scan is important in evaluating base-of-skull involvement and the possible presence of occult involved lymph nodes.

The most recent revision of the AJCC/Union Internationale Contre le Cancer (UICC) staging system recognizes the uniqueness of nasopharyngeal carcinoma among other head and neck tumors. Both the criteria for T and N staging have been revised, as has the stage grouping. These are summarized in .