The diagnosis of Thornwaldt's cyst.

Thornwaldt's cyst is an uncommon nasopharyngeal lesion which develops from the remnant of the primitive notochord. A case report of a patient with a Thornwaldt's cyst and cervical adenitis is presented. Though computed tomography of the head and neck was unremarkable, magnetic resonance imaging of the nasopharynx revealed the Thornwaldt's cyst, suggesting that this modality may be more sensitive in detecting and evaluating cystic lesions of the nasopharynx. The differential diagnosis of cystic nasopharyngeal masses is discussed.