Head and Neck Imaging

Nasopharynx cancer

Overall, malignant nasopharyngeal tumours are uncommon, but a much higher incidence of nasopharyngeal cancer is seen along the south-east coast of China, including Hong Kong and Macao. An association with the EpsteinBarr virus is observed, but other risk factors have also been reported. The age distribution is much younger than for other head and neck cancers.

Nasopharyngeal carcinoma has a lymphoid stroma, and is also known as undifferentiated carcinoma of nasopharyngeal type or lymphoepithelioma.

Clinical picture

The most common presenting symptom is a neck mass (caused by neck adenopathies). Nasal obstruction is also common; epistaxis may be present. Hearing loss secondary to dysfunction of the eustachian tube may also be the first symptom; unilateral serous otitis media in an adult patient should always raise the possibility of a nasopharyngeal tumour. With disease progression, other symptoms may arise, such as those caused by skull base invasion (dysfunction of cranial nerves) or by orbital invasion.

Diagnostic imaging

Imaging is required for both staging and treatment planning. MRI is the preferred imaging modality, but complementary CT may be needed for evaluation of early bone invasion.

Many of these tumours arise in Rosenmullers fossa. Lateral spread through an anatomical opening in the pharyngobasilar fascia, provides access to the parapharyngeal space) and is commonly seen (Fig.1); from here, the mass may spread to the skull base or progress towards the masticator space. Direct superior extension in or through the skull base is seen in about one quarter of patients; this commonly occurs at the level of the foramen lacerum and/or petroclinoid fissure (Fig.2). Inferior extension along the pharyngeal walls, and anterior spread to the nasal cavity are also common. Nearly all patients have lymphatic spread at presentation; the retropharyngeal lymph nodes are nearly always the first involved (see retropharyngeal space).

Treatment

Nasopharyngeal carcinoma is treated by radiotherapy. The control rates are higher for lymphoepithelioma than for squamous cell carcinoma head and neck at other head and neck sites.

RH

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Fig.2

Coronal contrast-enhanced CT images. Nasopharyngeal cancer, eroding through the foramen lacerum to reach the cavernous sinus region (arrow, a). Note lateral infratemporal extension; the tumour also extends to the middle cranial fossa via the foramen ovale (arrowhead, b).
Nasopharynx cancer, Fig.1
Nasopharynx cancer, Fig.2 (a)
Nasopharynx cancer, Fig.2 (b)