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Neuroradiology Case of the Week

Case 47

Karin Westesson, Kha Nguyen, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: A 53-year-old female presented with dizziness, headaches, and vomiting. A MRI of the brain was obtained to evaluate for an intracranial cause of these symptoms.

Radiological Findings: Images of the brain did not show any abnormality that could account for the patient’s symptoms. There was an incidental finding of a cystic lesion in the soft tissues of the posterior nasopharynx without mass effect or enhancement.

Diagnosis: Tornwaldt’s cyst

Discussion:  A Tornwaldt’s (or Thornwaldt’s) cyst is a benign developmental lesion [1,2] that is generally located on the posterior wall of the nasopharynx [1] on the midline. There is no sex differentiation and the peak occurrence is in patients 15-30 years old. It is related to the embryogenesis of the notochord. During development of a cyst, the notochord comes into contact with the endoderm of the primary pharynx before it reaches the prechordal plate. As a result, there is a small outpouching of pharyngeal mucosa directed toward the brain. If there is an adhesion that develops between the notochord and the endoderm when the notochord retracts [2] into the clivus and cervical spinal column, then a small portion of nasopharyngeal mucosa is carried with it, forming a midline diverticulum, which is lined with pharyngeal mucosa. When the patient develops pharyngitis, the orifice of the diverticulum swells and subsequently closes, forming a cyst. The contents of a cyst are generally high in protein and anaerobic bacteria. Because of this, a Tornwaldt’s cyst appears bright on both the T1W and T2W MRI images. Patients with cysts are generally asymptomatic and need not be treated [2].
   Several factors, such as trauma, can however cause the pressure inside the cyst to increase and make the patient symptomatic [1]. When the pressure is increased, the cyst bursts and releases the anaerobic contents into the nasopharynx [2]. Symptoms are upper respiratory tract infection, nasal obstruction, halitosis, a feeling of ear fullness [1] and prevertebral muscle spasms. Treatment of symptomatic cysts may involve using intraoral devices or surgical removal for chronically infected and painful cysts [3].

References:

1. Miyahara, H, Matsunaga, T. Tornwaldt’s Disease. ACTA Otolaryngol. 1994; Suppl. 517: 36-9.
2. Mukherji, Suresh K. “Pharynx. ” In: Head and Neck Imaging, 4th Ed. Ed. Som, Peter M., Curtin, Hugh D. St. Louis: Mosby, 2003. 1507-1509.
3. Yousem, David M. Case Review: Head and Neck Imaging. St. Louis: Mosby, 1998.