Clinical History
Routine MR follow up exam in a patient treated 6 years before for a parotid malignancy
Imaging Findings
A 40 years old man treated 6 years before for an adenoid cystic carcinoma of the parotid gland treated by surgery and radiotherapy underwent a routine MR follow up exam. Clinical examination was normal.
Discussion
Clinical presentation .
Tornwaldt’s Cyst (1) usually appears as an asymptomatic, incidental finding on MR of the head.The incidence is currently estimated at 4%. Tornwaldt's disease is an inflammation or abscess of the embryonic remnant cyst of the pharyngeal bursa appearing at the posterior median wall of the nasopharynx. Although many cases are symptom-free, symptoms can often be caused by nasal tamponade, trauma, adenotomy, or other mechanical stimuli. Symptoms are those of upper respiratory tract infection with obstinate occipital pain, purulent choanal discharge, nasal obstruction, expiratory whistle, halitosis, feeling of ear fullness, clearing of the throat, dysfunction of the eustachian tube, sometimes associated with middle-ear infection (2).
Pathologic findings.
Tornwaldt's bursae or nasopharyngeal bursae originate at the interface between the embryonic tissue from which the vertebrae develop (the notochord), and the developing foregut. If the opening through which the bursa drains into the nasopharynx becomes obstructed, a Tornwaldt's cyst will develop. Tornwaldt’s cyst is present in 4% of all autopsy specimens (3).
Imaging features.
Seen as a midline cystic mass in the upper nasopharynx, nestled between the prevertebral muscles within the pharyngeal raphe. The cyst may be a few millimeters to several centimeters in diameter. Smaller cyst are not seen on CT, whereas MRI clearly delineates the cyst in most cases.
The T1 signal of Tornwald’s cyst varies from hypointense to hyperintense, probably resulting from the amount and type of protein within the cyst.
The cysts had high signal intensity on T1-weighted, T2-weighted, and fluid-attenuated inversion-recovery images.(4)
Posterior rhinoscopy, simple lateral view X-ray tomography, nasopharyngeal fibroscopy, CT scan and MRI can be useful in showing adhesion to the cervical vertebrae.
Treatment
Complete extirpation via a transpalatal approach, or simple incision or excision of the cyst is desirable when they are clinically symptomatic (Tornwaldt's disease)(5). They are not treated when they are incidental finding such as in our case.
Differential Diagnosis List
