A Thornwaldt cyst (also spelled Tornwaldt cyst or bursa) is a common, non-cancerous developmental finding. This benign lesion is typically present from birth and rarely causes health problems. The vast majority of these cysts remain small and asymptomatic throughout a person’s life, often discovered accidentally during imaging for unrelated conditions. It is primarily a structural anomaly that only requires attention if it becomes infected or grows large enough to interfere with normal function.
Defining the Thornwaldt Cyst
A Thornwaldt cyst is a benign, midline cystic swelling located on the roof of the nasopharynx, the area behind the nose and above the soft palate. This structure represents a remnant of the pharyngeal bursa, also known as Luschka’s Bursa, that forms during embryonic development. Its formation is specifically linked to the retraction of the notochord where it briefly contacts the endoderm of the primitive pharynx around the tenth week of gestation.
The cyst develops when the opening of the pharyngeal bursa becomes obstructed, preventing normal drainage into the nasopharyngeal cavity. This obstruction, which can be mechanical or inflammatory, leads to an accumulation of fluid and proteinaceous content within the cyst’s lining of respiratory epithelium. These lesions are usually nestled between the longus capitis muscles and typically range from two to ten millimeters in diameter.
Recognizing Symptoms and Diagnosis
Thornwaldt cysts frequently remain undiagnosed due to their small size and lack of symptoms. When symptoms do occur, they are typically mild and emerge if the cyst becomes infected or enlarged. An infected cyst may lead to a persistent post-nasal drip, a foul taste, or bad breath (halitosis) resulting from the discharge of purulent fluid.
If the cyst grows substantially, it can cause physical obstruction. This potentially leads to symptoms like mild ear fullness, muffled hearing, or nasal blockage due to interference with the Eustachian tube. Other reported symptoms include occipital headache and neck muscle stiffness. Because the symptoms are often non-specific, the cyst is typically discovered incidentally during an examination or imaging performed for other reasons.
Diagnosis is confirmed using imaging studies, which help differentiate the cyst from other nasopharyngeal masses, such as meningoceles or encephaloceles. Magnetic Resonance Imaging (MRI) is considered the gold standard for diagnosis because it clearly visualizes the cyst’s fluid content, size, and relationship to surrounding structures. A nasopharyngoscope, a flexible viewing tube inserted through the nose, can also be used to visualize the smooth, well-encapsulated lesion directly.
Management and When Intervention is Necessary
For the majority of individuals with a Thornwaldt cyst, no treatment is necessary because the lesion is asymptomatic and poses no threat to health. The recommended course of action is watchful waiting, where the cyst is simply monitored, often without the need for follow-up imaging. Treatment is only considered when the cyst causes persistent, noticeable symptoms or grows large enough to cause significant structural obstruction.
Surgical intervention is the management strategy for symptomatic cases, regardless of the cyst’s size. The primary goal of intervention is to relieve symptoms by establishing permanent drainage of the accumulated fluid. The preferred surgical technique is marsupialization, which involves making an opening in the cyst and folding back the edges to create a new, permanent pathway for drainage.
The procedure is typically performed endoscopically through the nose, offering a minimally invasive approach with excellent visualization. Complete excision of the cyst is an alternative, but marsupialization is often sufficient and effective for symptom resolution. Antibiotics may be used to treat any active infection before or after the procedure, ensuring a complete resolution of the inflammation that caused the symptoms.