Imaging of nasopharyngeal inflammatory pseudotumours: differential from nasopharyngeal carcinoma

The purpose of this study was to describe the MRI findings of inflammatory pseudotumours (IPTs) involving the nasopharynx and to differentiate IPTs from nasopharyngeal carcinoma (NPC). The medical records and imaging studies of 7 patients (6 men, 1 woman; age range, 32-71 years; mean age, 52.4 18 years) with IPT involving the nasopharynx were reviewed retrospectively. The MRI findings were compared with those of seven patients with advanced NPC with skull base invasion. All patients with IPT involving the nasopharynx presented with single or multiple cranial neuropathies; six reported pain; and four patients had a recent history of otitis media. Three were initially misdiagnosed as having NPC according to MRI findings, and all underwent nasopharyngeal biopsy to exclude malignancy. 7/7 (100%) patients received systemic corticosteroid treatment; 7/7 (100%) showed initial rapid resolution of clinical symptoms or radiographical findings; 3/7 (42.9%) had resolution of all signs and symptoms; 3/7 (42.9%) still have limited residual symptoms; and 1/7 (14.3%) suffered recurrence 3 years after remission. The characteristic MR findings of IPT include an infiltrative growth pattern, minimal to mild mass effect, hypointensity on T-2 weighted images, and moderate homogeneous enhancement after contrast administration. Intact nasopharyngeal mucosa, internal carotid artery encasement and narrowing, extensive pachymeningeal thickening and a relative paucity of associated neck lymphadenopathy are additional MR findings that favour the diagnosis of IPT rather than NPC. In conclusion, IPT involving the nasopharynx has characteristic MR findings which, together with clinical and laboratory presentations, are helpful in differentiating IPT from malignant tumours, especially NPC.