ThornwaldtCyst — Overview – Rodrigo Arrangoiz MS, MD, FACS, FSSO

Definition:
- A benign, midline nasopharyngeal cyst:
  - Arising from remnants of the embryonic notochord at the pharyngeal bursa
- It is superficial to the superior pharyngeal constrictor muscle and covered by nasopharyngeal mucosa
- The pharyngeal bursa forms from a communication between the notochord and nasopharyngeal endoderm:
  - Obstruction of the bursa orifice by inflammation, infection, or mechanical causes leads to cyst formation
- Histopathologically:
  - The cyst wall is lined by respiratory epithelium and infiltrated diffusely by lymphocytes without lymphoid follicles
Epidemiology:
- The pharyngeal bursa is present in approximately 3% of healthy adults
- In an MRI series of 3,000 patients:
  - Tornwaldt cysts were found in 6%:
    - With peak prevalence at age 51 to 60
- An earlier MRI series of 1,208 subjects:
  - Found a prevalence of 1.9%:
    - With a mean age of 57 years
- No significant gender predilection
Clinical Presentation:
- Most cases are asymptomatic and discovered incidentally on imaging
- When symptomatic (typically from infection or inflammation), presentations include:
  - Nasal obstruction and postnasal drip
  - Halitosis and unpleasant taste
  - Occipital headache
  - Eustachian tube dysfunction with hearing loss or middle ear effusion
  - Foreign body sensation in the nasopharynx
Diagnosis — Imaging:
- MRI is superior to CT for detection and characterization
- MRI features:
  - High signal on T1-weighted images (proteinaceous content)
  - High signal on T2-weighted images (isointense to CSF)
  - Hyperintense on FLAIR
  - Round or oval, mean size approximately 6 mm
  - No enhancement of cyst contents; thin rim enhancement may be seen with infection
- CT features:
  - Well-defined, hypodense midline nasopharyngeal lesion
  - Less sensitive than MRI
Key distinguishing feature from mucous retention cysts:
- Tornwaldt cysts are midline:
  - They are located in the posterior nasopharyngeal wall:
- Mucous retention cysts:
  - Are more commonly lateral or off-midline
- On nasopharyngoscopy:
  - Smooth, submucosal midline mass in the posterior nasopharynx
Differential Diagnosis:
- Mucous retention cyst (most common mimic)
- Nasopharyngeal carcinoma
- Minor salivary gland tumor
- Branchial cleft cyst
- Dermoid / epidermoid cyst
- Nasopharyngeal abscess
Treatment:
- Asymptomatic cysts:
  - Observation only:
    - No treatment required
- Symptomatic cysts:
  - Surgical intervention via transnasal endoscopic or transoral approach
- Marsupialization is the procedure of choice:
  - Preferred over complete excision to minimize recurrence
  - In a series of 21 patients treated with transnasal endoscopic marsupialization:
    - All had symptom resolution with no recurrence at 4-year follow-up and no intraoperative or postoperative complications
  - Antibiotics may be used as adjunct therapy for infected cysts prior to definitive surgical management
References:
- Cetinkaya EA. Thornwaldt Cyst. J Craniofac Surg. 2018.
- Righi S, Boffano P, Pateras D, et al. Thornwaldt Cysts. J Craniofac Surg. 2014.
- Chang SL, Wu TC, Yiu CY. Tornwaldt’s Cyst Formation After Concurrent Chemoradiotherapy for Nasopharyngeal Carcinoma. J Laryngol Otol. 2006.
- Sekiya K, Watanabe M, Nadgir RN, et al. Nasopharyngeal Cystic Lesions: Tornwaldt and Mucous Retention Cysts of the Nasopharynx: Findings on MR Imaging. J Comput Assist Tomogr. 2014.
- Ikushima I, Korogi Y, Makita O, et al. MR Imaging of Tornwaldt’s Cysts. AJR Am J Roentgenol. 1999.
- Turan S, Gürbüz MK, Kaya E, et al. Is Transnasal Endoscopic Marsupialization Sufficient in Thornwaldt Cysts? J Craniofac Surg. 2020.