A 21-year-old man with sublingual pain was referred for ultrasound. He had a history of symptomatic sialoadenitis and sialolithiasis for which he had surgical excision of the left submandibular gland 6 years ago.
Ultrasound showed the presence of a deep located well-defined midline suprahyoid cyst with some internal echoes, measuring 12 x 20 mm (Figure 1). A normal thyroid gland was appreciated. Additional CT of the neck with IV contrast showed the presence of a well-defined, thin-walled oval cystic mass of 14 x 20 x 15 (AP x LR x CC) (Figure 2-4). The cyst is visible on the lingual side of the epiglottis within the vallecula, left more than right. On a previous CT neck from 7 years earlier (not shown), the cystic lesion was retrospectively seen and was only minimally increased in size. Additional fibroscopy revealed a cystic-like mass in the left vallecula (Figure 5).
Based on the serial imaging and fibroscopic findings the diagnosis of a vallecular cyst was made.
Laryngeal cysts embody approximately 5% to 10% of benign laryngeal lesions. Laryngeal cysts are often located on the true vocal cords, the lingual surface of the epiglottis and in the vallecula. Histologically the cyst wall contains respiratory or stratified squamous epithelium.  Children with vallecular cysts typically present with feeding difficulties, failure to thrive, inspiratory stridor and laryngomalacia. Early diagnosis is necessary since it may lead to life-threatening airway obstruction if left untreated. Adults may be asymptomatic or present with difficulty swallowing, foreign body sensation, referred otalgia or stridor. Sometimes it is difficult to clinically differentiate a cyst from a solid mass and imaging is therefore essential for the diagnosis.
On ultrasound, they present as well-defined anechoic lesions in the region of the epiglottic or vallecula. On CT they appear as a well-defined mass with fluid density. When the cyst is infected it may demonstrate debris and on CT increased density and peripheral enhancement.
A vallecular cyst located in the midline may be difficult to distinguish from a thyroglossal duct cyst. However, a thyroglossal duct cyst follows the embryologic course of thyroid descends and is located at the foramen cecum or more anteriorly between the strap muscles and hyoid bone. Epidermoid or dermoid cysts are also midline lesions, but they are usually located in the floor of mouth or less frequently superficially in the subcutaneous tissue of the anterior neck. Moreover, dermoid cyst generally contains internal calcification and fat. On ultrasound epidermoid has a pseudosolid appearance and dermoid appears inhomogeneously hyperechoic and may show calcifications. A lymphatic malformation is a cystic lesion that rarely involves the epiglottis and is typically multilocular and transspatial. Small asymptomatic vallecular cysts do not need treatment. In our patient, the sublingual pain subsided and because of the long-term stable course, no further treatment was deemed necessary. Larger, symptomatic cysts can be treated with surgical excision, laser-assisted resection or marsupialization.
Written informed patient consent for publication has been obtained.
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