Thornwaldt Cyst, Report of a Typical Sample Case

Clinical History

A 27 year-old woman applied with complaints of dysphagia and a sense of a mass at her throat. She gave a story of about two months. She reported that this was her first application to a hospital for these complaints of hers.

Imaging Findings

Our case is a 27 year-old woman. She applied with complaints of dysphagia and a sense of a mass at her throat. She gave a story of about two months. She reported that this was her first application to a hospital for this reason. Her clinical instrumental examination revealed the presence of a bulging at the nasopharynx. She then was referred to the radiology department for an MR study. We performed axial and sagittal scans with T1 and T2- weighted, and also FLAIR, sequences. On all the scans, a bulging mass-like lesion of about 1-1.5 cm of size at the posterior nasopharyngeal wall could easily be seen. The mass brightened up on all sequences, but its most hyperintense mode was the T2-weighted scan. The lesion's hyperintensity on both spin-echo sequences was typical for a Thornwaldt cyst. The lesion was excised, and the true nature of the mass was approved.

Discussion

The Thornwaldt cyst is a congenital pouch/cyst lined by ectoderm within the nasopharyngeal mucosal space. It is a benign developmental lesion that is generally located on the posterior wall of the nasopharynx. It is in fact a persistent focal adhesion between the notochord+ectoderm extending to the pharyngeal tubercle of the occipital bone. The incidence of the lesion is 4% of autopsies. There is no sex differentiation and the peak age of incidence is 15-30 years. It is related to the embryogenesis of the notochord. If an adhesion takes place when the notochord retracts into the clivus and cervical spinal column, then a small portion of the 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 Thornwaldt cyst are generally high in protein. Because of this, a Thornwaldt cyst appears bright on both the T1W and T2W magnetic resonance (MR) images. MR is the modality of choice in the diagnosis of a Thornwaldt cyst. Main MR findings are as follows: smoothly marginated cystic mass of a few mm to 3 cm in size, a non-enhancing lesion which is hyperintense on both T1 and T2-weighted sequences, and no bone erosion. Our case had all these characteristic findings, and thus, it was a typical sample case. A Thornwaldt cyst may be asymptomatic and thus the diagnosis an incidental one. But there may also be a symptomatology. Several factors, such as trauma, can cause the pressure inside the cyst to increase and make the patient symptomatic. These symptoms may include infection, persistent nasopharyngeal drainage, halitosis, foul taste of mouth, nasal obstruction, a feeling of ear fullness, upper respiratory tract infection, prevertebral muscle spasms, etc. Treatment of symptomatic cysts may involve using intraoral devices or surgical removal of infected and painful cysts. The typical location for the cyst is the posterior roof of te nasopharynx. Rathke pouch cysts must be considered in the differential diagnosis. These cysts occur in the craniopharyngeal canal anteriorly and cephalad to Thornwaldt cysts.

Differential Diagnosis List

Final Diagnosis

Thornwaldt cyst

URL:	https://eurorad.org/case/5943
DOI:	10.1594/EURORAD/CASE.5943
ISSN:	1563-4086