On imaging, these lesions are generally characterized as well-defined, thin-walled, fluid or air-filled cystic lesions in the paraglottic space. The communication with the laryngeal ventricle is not always identified, and an extra laryngeal extension through the thyrohyoid membrane may or may not be present.
Almost all laryngoceles are unilateral, only eight bilateral cases have been reported in the medical literature. Incidence appears to be equally distributed between men and women, and they are most common in mid to later life .
When small, the lesions are usually asymptomatic and incidentally discovered when imaging the neck for other reasons. Symptoms vary accordingly to the size and extension of the lesion and may include: a sore throat, dysphagia, stridor, neck lump, and/or airway obstruction.
Laryngoceles are usually acquired rather than congenital. They are lined by pseudostratified, columnar, ciliated epithelium. Occasional areas of stratified squamous epithelium +/- submucosal serous and mucous glands may be present.
Three laryngocele subtypes are described :
- internal (or simple): the dilated ventricular saccule is confined to the paralaryngeal space; it is contained by the thyrohyoid membrane (~40%)
- external: the saccule herniates through the thyrohyoid membrane, and the superficial portion is dilated (~25%)
- mixed: with dilated internal and external components (~45%)
Raised intralaryngeal pressure secondary to:
- excessive cough
- playing woodwind/brass instruments
- glass blowing
- obstructing lesion, e.g. a tumor
- childbirth: rarely reported
The finding of a laryngocele should prompt a search for an underlying laryngeal carcinoma obstructing the orifice of the laryngeal ventricle . Secondary laryngocele is the term used when a tumor is the cause of a laryngocele.
Laryngoceles are better appreciated on radiographs when they contain air. In these cases, an air pocket may be observed in the upper cervical paralaryngeal soft tissues.
Typically seen as a well defined, air or fluid-filled lesion related to the paraglottic space, which has continuity with the laryngeal ventricle. The extent will obviously depend on subtype.
Attenuation characteristics may vary depending on laryngocele content, whether air, fluid and/or mucus.
Same morphological characteristics observed on CT, usually:
- T1: low signal
- T2: high signal
- T1C+ (Gd): absent-to-minimal linear peripheral enhancement; when thick enhancing walls are present, consider pyolaryngocele
Treatment and prognosis
Surgical excision may become necessary if a laryngocele is symptomatic .
- infection: infected laryngocele is known as a pyolaryngocele
- occurs in around 8-10% of laryngoceles
- infection within a laryngocele can spread to adjacent head and neck spaces and can lead to supraglottitis
- increased risk of laryngeal carcinoma
Imaging differential considerations include: