Clinical History
52-year-old male patient with type 2 diabetes mellitus, hypercholesterolaemia and tobacco abuse in study for symptoms of gastroesophageal reflux without dysphagia.
Imaging Findings
A mass in the right vallecula is incidentally discovered during a barium oesophagogastroduodenography ordered to study the gastroesophageal reflux of the patient. It is a round, smooth, well defined submucosal mass which measures 36 x 21mm.
A CT is also performed and shows a well-defined round hypodense mass in the pharyngeal mucosal space, in the right vallecula.
Discussion
Retention cysts are the most frequent benign lesions of the pharyngeal mucosal space [1, 2]. They are frequently located in the valleculae or in the aryepiglottic folds [1, 2] and they are usually found in adults [3].
Retained secretions and chronic inflammation of a seromucinous gland duct are the aetiology of these lesions [2, 3].
The cysts have an epithelial lining and are filled with serous or mucous fluid. They may also contain old blood products or proteinaceous fluid [1, 3]. Usually, cysts are very small, measuring millimetres, but occasionally they can reach 2-3cm [3, 4], as in this case.
They are usually asymptomatic, so that the most frequent presentation is as an incidental finding in a patient studied for any other reason [1-5]. Knowledge of this kind of lesions makes further studies redundant.
Less frequently a retention cyst may cause dysphagia, dysphonia or respiratory symptoms; there are even rare cases of pedunculated cysts that may occlude the larynx [1, 2]. The bigger the lesion the more frequent the symptoms [2].
The imaging findings are usually enough to make the diagnosis of retention cyst [2]. They appear as round or oval, smooth surfaced and well circumscribed masses [2, 3].
Occasionally, especially with large or complicated cysts, a differential diagnosis should be made with other more uncommon lesions of the pharynx. Entities that may also be found at this location include: benign tumours of minor salivary glands, granular cell tumour, ectopic thyroid tissue, thyroglossal duct cyst, saccular cyst, chondroma, lipoma, neurofibroma, hamartoma, oncocytoma, lymphoepithelial cyst, among others [1-4, 6].
Some of these lesions can be ruled out taking into account other features: neurofibromas should be considered in the context of a neurofibromatosis; chondromas arise from cricoid cartilage; hamartomas, ectopic thyroid tissue and thyroglossal duct cysts at the tongue base are located in the midline; lipomas have fat density whereas ectopic thyroid tissue and other tumours are usually solid on TC. [1, 3]
In some cases complementary studies (otolaryngologic examination) are required to confirm the benign nature of the lesion and rule out malignant pathology [1, 2].
If the patient is symptomless there is no need of treatment [2, 3]; otherwise the mass may be surgically excised. The recurrence rate of retention cysts treated with surgery is very low [2].
The cystic mass in our patient was surgically excised. The pathologist confirmed its benign nature.
Differential Diagnosis List
Retention cyst in the right vallecula.
Granular cell tumour
Benign tumour of the minor salivary gland
Ectopic thyroid tissue
Thyroglossal duct cyst
Lipoma
Saccular cyst of the larynx
Others
Final Diagnosis
Retention cyst in the right vallecula.
