|Mid sagittal T1 and T2 images of cervical spine: Small, well defined thin walled T1 isointense and T2 hyperintense cyst in midline in nasopharynx- s/o Thornwaldt's cyst|
Wednesday, 13 June 2012
· Benign developmental lesion that is generally located on the posterior wall of the nasopharynx on the midline.
· No sex differentiation and the peak occurrence is in patients 15-30 years old.
· 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 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.
· When the pressure is increased, the cyst bursts and releases the anaerobic contents into the nasopharynx.
· Symptoms are upper respiratory tract infection, nasal obstruction, halitosis, a feeling of ear fullness and prevertebral muscle spasms.
· Treatment of symptomatic cysts may involve using intraoral devices or surgical removal for chronically infected and painful cysts.
· T1 signal is variable depending on the protein content. Hyperintense on T2 sequence with no enhancement with contrast.
Reference: “Pharynx. ” Head and Neck Imaging, 4th Ed. Ed. Som, Peter M., Curtin, Hugh D. St. Louis: Mosby, 2003. 1507-1509.