Tornwaldt's cyst: Clival erosion with reconstitution after treatment

1. Case report 

The patient is a 6-year-old Caucasian female with no significant past medical history who presented with a 1 month history of paroxysmal, sharp, throbbing headaches radiating from the occipital region to the top of the head. The patient denied any history of nausea, vomiting, fevers, or chills. There was no history of visual changes, hearing changes, or recent trauma. Movement of her head seemed to worsen her symptoms. Treatment of headaches with ibuprofen and acetaminophen was not helpful.

One week prior to our assessment, the patient had undergone a MRI of the head while in the emergency room which revealed no abnormalities. Subsequent MRI of the neck and cervical spine revealed an abnormal signal and soft tissue thickening anterior to the skull base (Fig. 1). A CT scan with contrast revealed a 0.5cm×1.5cm×1.1cm nasopharyngeal cystic mass anterior to the clivus with cortical destruction of the anterior and mid-clivus (Fig. 2). The patient was scheduled for image guided biopsy of the nasopharyngeal mass.

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Fig. 1. Sagital T2-weighted MRI of cervical spine showing Tornwaldt's cyst as a hyperintense lesion posterior to adenoid tissue and soft tissue thickening anterior to the skull base.

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Fig. 2. CT with contrast of a Tornwaldt's cyst showing a 0.5×1.5×1.1cm cystic mass of the nasopharynx with cortical destruction of the anterior and mid-clivus (arrow). (A) Axial CT neck with contrast bone window. (B) Axial CT neck with contrast soft tissue window. (C) Sagital reformatted CT neck with contrast bone window.

In the operating room, adenoid tissue surrounding the cystic mass was removed using an adenoid curette. Upbiting forceps were then used to take multiple biopsies of the mass. The removed adenoid tissue and biopsies were sent to pathology. Purulent drainage was noted to come from the mass during biopsies. Cultures of the drainage were obtained and sent for analysis. No complications occurred during the procedure. When the procedure was completed, the patient was admitted to the hospital for 2 days for observation. During this time intravenous ampicillin/sulbactam was given empirically. The biopsy results of the cyst overlying the clivus were consistent with that of an infected Tornwaldt's cyst. Culture results revealed normal nasopharyngeal flora. After 2 days, the patient was asymptomatic and discharged to home on amoxicillin/clavulanate by mouth for 1 week.

During 6 months of follow up, the patient's occipital headaches have resolved completely. Follow up CT scans have revealed resolution of the prior cystic mass and near complete resolution of the bony defect involving the clivus (Fig. 3).

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Fig. 3. Sagital CT of neck, 6 months post-op, showing resolution of prior cystic mass and clivus defect.

2. Discussion 

Nasopharyngeal cysts are an uncommon entity that is often found incidentally on radiological studies or on nasal endoscopy. These cysts are frequently asymptomatic until they become large in size or infected. The differential of a midline nasopharyngeal cyst as presented above includes not only Tornwaldt's cyst, but also adenoid retention cyst, Rathke's pouch cyst, oncocytic cyst, seromucinous cyst, and encephalocele. Though uncommon, symptomatology of these cysts is among the most common we encounter in our daily clinical practice. The most common symptoms include fullness in the ear, tinnitus, nasal obstruction, dysphagia, dysarthria, dysphonia, odynophagia, halitosis, cephalgia, or stiffness of cervical muscles [2], [3]. For this reason, nasopharyngeal cyst should be considered in our differential when encountering these symptoms.

Tornwaldt's cyst are a subtype of nasopharyngeal cysts. They are thought to form when the pharyngeal bursa becomes occluded. These cysts were named after Gustav Ludvig Tornwaldt who was the first to recognize the significance of the pharyngeal bursa and the pathology that may involve it [1]. Typically around the sixth week of development the connection between the notochord, which forms the axial skeleton, and the pharynx separates. Occasionally a remnant of this tract persists resulting in a pharyngeal bursa. These bursae are located cephalic to the superior pharyngeal constrictors. It is theorized that this bursa becomes obstructed from either inflammation or even scarring from adenoidectomy. The location of the bursa near the fossa of Rosenmuller and between the longus capitis muscles explains some symptoms such as eustachian tube dysfunction and neck stiffness.

Tornwaldt's cysts are often identified incidentally. The overall incidence of Tornwaldt's cyst has not been clearly established. Many of the older studies done by autopsy from the 1940 to 1960s had suggested 1.4–3.3% incidence [5], [6]. A study completed at the University of Virginia Health Sciences Center from 1994 until 1999 by examining 31,855 CTs and 21,158 MRIs concluded that the overall incidence may be closer to 0.06% [4]. Many have questioned the wide discrepancy. One theory is that the incidence of these cysts may in fact be decreasing. This may be in part secondary to increased use of folic acid during pregnancy. Folic acid may inhibit abnormal notochord development that leads to the eventual development of Tornwaldt's cyst, as it does in the prevention of spinal cord defects such as spina bifida [7].

MRI remains the study of choice for imaging the nasopharynx [8]. Studies have shown that a greater percentage of Tornwaldt's cysts are detected on MRI when compared to CT [4]. These cysts can appear anywhere from isointense to hyperintense on T1-weighted MRI studies depending on the protein content of the cyst. On T2-weighted MRI studies, these cysts appear hyperintense. If gadolinium injection is used during a MRI, the contents of the cyst will not enhance in relation to the nasopharyngeal mucosa. Tornwaldt's cysts appear as isointense masses similar to cerebrospinal fluid on CT. Intravenous contrast injection also does not enhance the appearance of these cysts on CT [8].

Tornwaldt's cysts differ in histology when compared to other midline nasopharyngeal cysts. These cysts consist of a respiratory mucosal lining on one surface and an epithelial lining on the other, separated by connective tissue in between. There is little if any lymphoid tissue present. In contrast, adenoid retention cysts consist largely of lymphoid tissue [1]. Seromucinous cysts consist of respiratory and/or squamous epithelium associated with secreting mucous gland [5]. Oncocytic cysts are formed by two layers of large epithelial cells and eosinophilic granular cytoplasm [9].

Treatment of Tornwaldt's cysts is recommended only for those that are symptomatic. Asymptomatic cysts may just be incidental findings on radiologic studies and require no intervention. Treatment consists of drainage of the cysts with marsupialization. Transpalatal excision and electrocoagulation also have been described [3].

3. Conclusion 

Tornwaldt's cysts are relatively uncommon midline nasopharyngeal cysts that should be included in a physician's differential diagnosis for some of the clinical symptoms encountered most commonly including headaches. This case report represents one such case. Persistent occipital headaches secondary to a Tornwaldt's cyst has been reported in the literature. Evidence of cortical destruction of the clivus secondary to a Tornwaldt's cyst with bony reconstitution following treatment has not been previously documented.