Pharyngocele: CT and MRI findings. (Imaging Clinic).

Differentiating a pharyngocele from a laryngocele can be difficult given that both entities appear clinically in a similar manner. (1) A laryngocele develops when the lateral sacculus or appendix of the laryngeal ventricle enlarges or dilates as a result of increased intraglottic pressure secondary to excessive coughing or blowing. A less common cause of a laryngocele is obstruction of the proximal sacculus by postinflammatory stenosis, trauma, or a tumor. The cystic mass of a laryngocele may be filled with air, fluid, or inflammatory material. Depending on their location in the pharyngolaryngeal area, pharyngoceles and laryngoceles can be classified as internal, external, or mixed. A laryngocele penetrates the thyrohyold membrane and enters the lateral neck in the submandibular area the same way a pharyngocele does. (1, 2) In some cases, patients develop both a pharyngocele and a laryngocele.

Pharyngoceles can arise from two weak areas on both sides of the pharynx. One of these areas is at the junction between the superior and middle pharyngeal constrictor muscles. When the ostium of a pharyngocele is located in this area, it is usually situated on the internal surface of the pharynx, in the region inferior to the lower pole of the tonsil and at the lateral side of the vallecula. The other weak area is in the inferiorportion between the middle and inferior pharyngeal constrictor muscles. The ostium of a pharyngocele that originates in this area will be located at the base of the piriform sinus. An important point to keep in mind is that pharyngoceles and laryngoceles that originate in this inferior weak area will protrude through the thyrohyoid membrane, which makes their differentiation difficult.

A pharyngocele can appear as a mass and is usually associated with various symptoms, including dysphagia, hoarseness, cervical pain, regurgitation, dysphonia, cough, earache, and odynophagia. In some cases, however, pharyngoceles (and laryngoceles) are asymptomatic. Pharyngoceles manifest more often in men than in women (the male-to-female ratio ranges between 3:1 and 8:1), and they usually arise during the fifth and sixth decades of life (although some cases in young adults have been reported). (1,4) A loss of muscle elasticity with aging, a previous surgery, and an increase in intrapharyngeal pressure all play important roles in the pathogenesis of this anomaly. (3,4)

When a pharyngocele is suspected in a patient with such a clinical history, the diagnosis can be confirmed by various imaging studies, including plain x-rays, barium swallow, endoscopy, computed tomography (CT), and magnetic resonance imaging (MRI). Multiplanar MRI could prove to be more specific than the other modalities in making an anatomic identification of the location and characteristics of these lesions (figure).

References

(1.) Ward PH. Bilateral laryngoceles in a young trumpet player: Case report [letter]. Ear Nose Throat J 2001;80:132.

(2.) Harnsberger HR. Cystic masses of the head and neck: Rare lesions and characteristic radiologic features. In: Harnsberger HR. Handbook of Head and Neck Imaging. 2nd ed. St. Louis: Mosby, 1995:199-223.

(3.) Chevallier P, Motamedi JP, Marcy PY, et al. Sonographic discovery of a pharyngocele. J Clin Ultrasound 2000;28:101-3.

(4.) van de Ven PM, Schutte HK. The pharyngocele: Infrequently encountered and easily misdiagnosed. J Laryngol Otol 1995;109:247.9.