T2 hypointense lesions in the parapharyngeal space: a diagnostic challenge.

The parapharyngeal space is a complex anatomical site in the head and neck which may harbour clinically occult pathology given its deep-seated location. The vast majority of parapharyngeal space lesions are of intermediate or hyperintense signal on T2W sequences. This review focuses on T2 hypointense parapharyngeal space lesions which are rare and may constitute a diagnostic dilemma. We present the differential diagnosis of these lesions, highlighting the pertinent radiological findings and identifying a histological correlation for the low T2 signal. A brief discussion of the physics principles accounting for these imaging features is also included. We propose a diagnostic algorithm to facilitate diagnosis and avoid unnecessary biopsy, whenever possible.