Head and Neck Imaging

Pseudotumour, extraorbital

a nonspecific inflammatory condition for which no identifiable local or systemic cause has been identified. Inflammatory pseudotumour most commonly involves the lung and orbit, but has been reported to occur in nearly every body site (see pulmonary pseudotumour, orbital pseudotumour).

In the head and neck, inflammatory pseudotumour rarely occurs outside the orbits. The most frequent symptoms are local swelling and pain. Involvement of the skull base and intracranial extension has been reported, resulting in cranial nerve neuropathy and/or ischaemic insults. Constitutional symptoms may be present.

The condition may mimic a malignant lesion, and may occur at sites which are difficult to biopsy; this may expose the patient to the risk of unneccessary and potentially mutilating surgery. The soft tissue masses do not reveal specific imaging features on CT or MRI (Fig.1). The distribution of the mass lesions in reported cases suggest a perineural spread pattern. The differential diagnosis includes lymphoma, Wegeners granulomatosis head and neck manifestation and squamous cell carcinoma head and neck; depending on the location, meningioma and sarcoidosis also need to be considered.

In confirmed cases of inflammatory pseudotumour conservative steroid therapy may relieve symptoms.

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Fig.1

Patient with history of pain, numbness and tingling paresthesias in the left side of the face. a. Gadolinium-enhanced axial T1-weighted spin-echo image of the nasopharyngeal region. An enhancing soft tissue mass (double arrows) is seen in the left side of the nasopharynx and in the parapharyngeal space, extending around the left internal carotid artery (single arrow), into the skull base (region of hypoglossal canal, arrowhead) and into the prevertebral muscles. The pterygoid muscles also show some enhancement. b. Gadolinium-enhanced axial T1-weighted spin-echo image. After a course of corticosteroids, the mass lesion clearly reduced in size. Slight infiltration of left pterygopalatine fossa and fat posterior to the maxillary sinus is seen. c. Axial nonenhanced T1-weighted spin-echo image obtained 5 months after figure 1b, while the patient was suffering from a recrudescence of symptoms. The lesion has reappeared and now extends into the left retromaxillar fat and pterygopalatine fossa (arrowheads). d. Gadolinium-enhanced fat-suppressed T1-weighted image obtained at the same time shows intraorbital extension (arrow) and slight thickening of left cavernous sinus (arrowhead), and no signal void in the left internal carotid artery. MR angiographic study (not shown) confirmed internal carotid artery occlusion (from: De Vuysere S., Hermans R., Crevits I., Sciot R., Marchal G.: Extra-orbital inflammatory pseudotumor of the head and neck: CT and MRI findings in three cases. AJNR American Journal of Neuroradiology 1999, 20: 1133-1139, with permission).
Pseudotumour, extraorbital, Fig.1 (a)
Pseudotumour, extraorbital, Fig.1 (b)
Pseudotumour, extraorbital, Fig.1 (c)
Pseudotumour, extraorbital, Fig.1 (d)