Laryngeal cyst, also known as laryngocele, laryngeal diverticulum, or laryngeal pneumatocele, is an abnormal dilation of the laryngeal saccule containing gas. In infants and young children, the laryngeal saccule is relatively large, typically measuring 6–8 mm, with some cases reaching 10–15 mm. An exceptionally large saccule is referred to as a congenital laryngeal cyst. In adults, the formation of a laryngeal cyst is often associated with congenital abnormalities of the laryngeal saccule combined with factors such as chronic coughing, trumpet playing, weightlifting, or laryngeal tumors, which increase pressure within the saccule and cause dilation. Based on the location of the cyst, it can be classified into three types: internal, external, and mixed. An internal laryngeal cyst is located within the larynx and has two subtypes. One subtype protrudes from the laryngeal ventricle, pushing the ventricular fold upward and obscuring the ipsilateral vocal cord, sometimes extending to the contralateral side and obstructing the glottis. The other subtype arises from the aryepiglottic fold, distorting the ipsilateral larynx and occasionally extending upward to the base of the tongue, situated in the vallecula. An external laryngeal cyst appears in the neck. This type usually emerges through the thyrohyoid membrane at the site of the superior laryngeal nerve and vessels, located below the hyoid bone along the anterior border of the sternocleidomastoid muscle. Alternatively, it may protrude through the cricothyroid membrane, situated below the thyroid cartilage. A mixed-type laryngeal cyst occurs both within the larynx and in the neck, connected by an isthmus at the thyrohyoid membrane.

Initially, there are often no symptoms, which only appear when the growth becomes significantly large. The most common symptoms of the intralaryngeal type are changes in voice, unclear speech, hoarseness, or loss of voice, often accompanied by a cough. Some patients may belch before speaking to utilize pharyngeal muscle contractions to expel air from the laryngocele. Larger laryngoceles may cause stridor and difficulty breathing. If the cyst becomes infected, there may be pain, tenderness in the larynx, foul-smelling breath, and severe coughing if secretions enter the larynx. The extralaryngeal type primarily presents as a round, protruding mass in the neck that varies in size, feels very soft to the touch, and gradually shrinks when pressed, often accompanied by a hissing sound of escaping air. The skin color remains normal, with no adhesion or tenderness, but if infected, there may be local redness, swelling, and tenderness. The mixed type exhibits symptoms of both types.

bubble_chart Diagnosis

The diagnosis of external and mixed types mainly relies on symptoms. If there is a cystic protrusion in the neck that feels soft and compressible, enlarges when straining, and yields gas upon puncture and aspiration, the diagnosis can be confirmed. Diagnosing the internal type is more challenging and requires careful observation under direct laryngoscopy. The key features include changes in the mass size with respiration—shrinking during inhalation and enlarging when forcefully exhaling. If the mass gradually shrinks when compressed with instruments such as a direct laryngoscope or probe, the diagnosis can be established. Neck X-rays can aid in diagnosis, showing a circular lucent area at the mass site. Lateral views provide clearer images for the internal type, while frontal views are better for evaluating the external type.

For the external laryngeal type, the cyst is removed via an external cervical approach. There are various treatment methods for the internal laryngeal type, such as excision under direct laryngoscopy, electrocautery, injection of sclerosing agents, or laryngofissure for removal, but the results are generally unsatisfactory. Currently, the preferred method is excision via an external cervical approach. For patients with breathing difficulties, the cyst should be immediately punctured or a tracheotomy performed. If there is concurrent infection, regardless of the presence of laryngeal obstruction symptoms, close observation is required in addition to antibiotic treatment, and a tracheotomy may be necessary during seasonal epidemics.

bubble_chart Differentiation

It is difficult to differentiate internal laryngocele from laryngeal cysts, but laryngeal cysts do not communicate with the laryngeal ventricle, their size does not change with respiration, and they do not shrink when compressed. Internal laryngoceles protruding from the laryngeal ventricle must be distinguished from laryngeal ventricle prolapse. Laryngeal ventricle prolapse is usually caused by inflammatory edema or hypertrophy of the laryngeal ventricle mucosa, which protrudes from the ventricle. Its characteristic feature is that it is always located at the opening of the laryngeal ventricle and can be pushed back into the ventricle with instruments, and its size does not change with respiration. External laryngoceles must be differentiated from branchial cleft cysts, thyroglossal duct cysts, and dermoid cysts. The main distinguishing feature is that laryngoceles vary in size rapidly and can shrink when manually compressed, whereas other cysts do not exhibit this characteristic. It is important to note that laryngoceles may coexist with laryngeal cancer.