Laryngocoeles refer to dilatations of the laryngeal ventricular saccule located in paraglottic space of supraglottis.
On imaging, these lesions are generally characterised 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 extralaryngeal extension through the thyrohyoid membrane may or not be present.
When small, those 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: sore throat, dysphagia, stridor, neck lump, and/or airway obstruction.
Laryngocoeles 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 laryngocoele subtypes are described 2 :
- internal (or simple): the dilated ventricular saccule is confined to the paralaryngeal space (~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. tumour
The finding of a laryngocoele should prompt a search for an underlying laryngeal carcinoma obstructing the orifice of the laryngeal ventricle 2. Secondary laryngocele is the term used when a tumour is the cause of a laryngocoele.
Laryngocoeles are better appreciated on radiographs when having an air content. In those 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 laryngocoele content (e.g. air, fluid, 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
- infection: infected laryngocoele is known as a pyolaryngocoele
- increased risk of laryngeal carcinoma
Imaging differential considerations include:
- 1. Glazer HS, Mauro MA, Aronberg DJ et-al. Computed tomography of laryngoceles. AJR Am J Roentgenol. 1983;140 (3): 549-52. AJR Am J Roentgenol (abstract) - Pubmed citation
- 2. Koeller KK, Alamo L, Adair CF et-al. Congenital cystic masses of the neck: radiologic-pathologic correlation. Radiographics. 19 (1): 121-46. Radiographics (full text) - Pubmed citation
- 3. Ash L, Srinivasan A, Mukherj SK. Radiological reasoning: submucosal laryngeal mass. AJR Am J Roentgenol. 2008;191 (3): S18-21. doi:10.2214/AJR.07.7047 - Pubmed citation
- 4. Harnsberger HR, Glastonbury CM, Michel MA et-al. Diagnostic Imaging: Head and Neck. Lippincott Williams & Wilkins. (2010) ISBN:1931884781. Read it at Google Books - Find it at Amazon