eRadiograph Volume 7: Imaging of Oral Cavity | Page 150

Malignant parapharyngeal space tumors: These may arise from minor salivary gland
rests in the parapharyngeal space. Liposarcomas may occur as the contents of this
space are fat however extremely rare.
Malignant lesions are usually infiltrative tumors directly invading adjacent spaces of
the neck. It is difficult to accurately classify these lesions as arising from the PPS due to
their infiltrative nature.
Extension of pathological process from other spaces to PPS: This is the
commonest pathology of the PPS. Secondary extension of pathological processes from
adjacent spaces via transfascial extension.
Parapharyngeal space abscess occurs secondary to infection in the palatine tonsil,
pharynx or teeth. On imaging extension of infection to the parapharyngeal space may
be seen as cellulitis or abscess formation. Differentiation is important as presence of an
abscess warrants drainage. As the infected process can extend posteriorly to involve
the carotid space with resultant jugular vein thrombosis, carotid artery
aneurysm/rupture or mediastinitis.

An important differential to a primary parapharyngeal space mass lesion is a deep lobe
parotid mass lesion extending into the parapharyngeal space. The presence of fat all
around the mass lesion is a key finding. This would indicate this is a primary mass lesion
of the parapharyngeal space. A mass lesion arising from the deep lobe of parotid
would displace the parapharyngeal space medially with a thin crescent of fat.

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Parapharyngeal Space

On imaging cellulitis is seen alteration of the fat – which appears dirty illdefined and
altered in signal intensity. There is an increase in the attenuation of fat on CT and a
decrease in high T1W signal on MRI. An abscess is seen as a well defined necrotic
lesion which is T1W1 hypo and T2W hyper with peripheral enhancement.