Head and Neck Imaging

Retropharyngeal space

1. Anatomy

virtual space behind the pharynx, limited anteriorly by the middle layer of the deep cervical fascia, and posteriorly by the alar fascia of the deep layer of the deep cervical fascia (see cervical fascias). The retropharyngeal space extends from the skull base to the level of the fourth thoracic vertebra, where the above-mentioned layers fuse. The retropharyngeal space contains the retropharyngeal lymph nodes and some fat. These nodes are organized into a lateral and medial chain. The retropharyngeal lymph nodes are typically found between the internal carotid artery and the prevertebral muscles. No retropharyngeal lymph nodes are present below the level of the hyoid bone.

2. Pathology

  • Inflammation

    This is most commonly seen in children. The infection begins in the lymphatic tissue of Waldeyers ring and spreads to the retropharyngeal lymph nodes, causing adenitis. These nodes may become suppurative and eventually cause retropharyngeal cellulitis or a retropharyngeal abscess. Also, see abscess retropharyngeal.

  • Congenital lesions

    A vascular malformation head and neck or haemangioma head and neck may involve the retropharyngeal space.

  • Benign tumours

    Very rarely seen; lipoma may be encountered.

  • Malignant tumours

    The most common cause of retropharyngeal malignancy is nodal spread of squamous cell carcinoma head and neck (Fig.1). This is most commonly seen in cancer of the posterior pharyngeal wall, but also in recurrent cancer at other neck sites. Rarely other malignancies spread to the retropharyngeal nodes; retropharyngeal adenopathy is sometimes seen in non Hodgkin lymphoma head and neck manifestation. Also, see level system of lymph node classification.

    Posterior pharyngeal wall cancer may invade the retropharyngeal space directly. Other non-nodal malignancy is very rare.

  • Pseudomass

    Retropharyngeal space oedema may be seen when there is a venous or lymphatic outflow obstruction of the neck (e.g. superior vena cava syndrome or after radiation therapy) (radiation therapy, tissue changes (VI:2), Fig. 1). The carotid artery may show pronounced tortuosity and extend into the retropharyngeal space; clinically, this may appear as a submucosal mass lesion.

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    Fig.1

    Axial contrast enhanced CT image (level of nasopharynx). Centrally necrotic adenopathy, lymphatic metastasis of recurrent laryngeal squamous cell carcinoma. A retropharyngeal adenopathy is typically situated between the prevertebral muscles (arrowhead) and the internal carotid artery (arrow).
    Retropharyngeal space, Fig.1