A Thornwaldt cyst (also spelled as a Tornwaldt cyst) is a common incidental benign midline nasopharyngeal mucosal cyst.
The lesion is developmental and usually asymptomatic. In most cases it is found incidentally and as such age of diagnosis represents age of imaging of the nasopharynx. Peak incidence has been variably reported between the ages of 15 and 60 years of age 1,3, presumably due to gradual accumulation of fluid following obliteration of the neck.
A Thornwaldt cyst has an autopsy prevalence of approximately 4%, with no gender predilection 3.
Thornwaldt cysts are almost always asymptomatic. However, if they become infected they can cause halitosis or periodic discharge of foul tasting fluid into the mouth. Some may present with otitis media due to obstruction of the eustachian tube.
A Thornwaldt cyst forms as a result of retraction of the notochord where it contacts with the endoderm of the primitive pharynx. Initially is forms a small diverticula. Eventually inflammation results in obliteration of the mouth, resulting in a cyst.
The cyst is lined by respiratory epithelium and accumulates with fluid with variable proteinaceous content.
These lesions have a characteristic appearance and should usually not be confused with more sinister pathology. Typically they are well circumscribed rounded lesions immediately deep to the mucosa. They are usually nestled between and anterior to the longus colli muscles they elevate the mucosa forming a convex surface into the nasopharynx. They are variable in size, ranging from a few millimetres to a few centimetres in diameter, but are typically 2 - 10mm in size 1,3.
On CT they appear as well circumscribed low density (fluid density centrally) and are non enhancing. If the fluid is protein rich, then it may be hyper-attenuating and even mimic a solid lesion.
Similarly, MRI demonstrates these cysts as being well circumscribed with a thin wall.
- T1 - signal is variable depending of protein content
- T2 - high signal
- T1 C+ (Gd) - no enhancement
Asymptomatic lesions require no treatment. If treatment is required then de-roofing the cyst (marsupialisation) is usually sufficient, and can be performed via a transnasal approach 4.
There is usually no real differential, however adenoidal / mucosal masses can sometimes have cystic components, and therefore the differential includes:
- normal / prominent adenoidal tissue
- mucous retention cyst
nasopharyngeal carcinoma (NPC)
- up to 12% NPC's are midline 2
- minor salivary gland tumours
- neurenteric cysts
It is named after Gustav Ludwig Thornwaldt, German physician, 1843-1910
- 1. Ikushima I, Korogi Y, Makita O et-al. MR imaging of Tornwaldt's cysts. AJR Am J Roentgenol. 1999;172 (6): 1663-5. AJR Am J Roentgenol (abstract) - Pubmed citation
- 2. Chin SC, Fatterpekar G, Chen CY et-al. MR imaging of diverse manifestations of nasopharyngeal carcinomas. AJR Am J Roentgenol. 2003;180 (6): 1715-22. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Som PM, Curtin HD. Head and Neck Imaging, Volume 1 und. Mosby. (2003) ISBN:0323009425. Read it at Google Books - Find it at Amazon
- 4. Wigand ME. Endoscopic Surgery of the Paranasal Sinuses and Anterior Skull Base. George Thieme Verlag. (2008) ISBN:3137494028. Read it at Google Books - Find it at Amazon
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