Pathology of the Head and Neck

Larynx and Hypopharynx Chapter 7 201An outpouching of the dorsal hypopharyngeal wallabove the upper oesophageal sphincter is known asZenker’s diverticulum (ZD). The condition is more oftenseen in northern Europe, especially the UK, thanelsewhere in the world [42]. The site of origin is betweenthe thyropharyngeal and the more horizontalpart of the cricopharyngeal muscle. The aetiologicalfactors of ZD occurrence have not been explained, butan incomplete sphincter opening with an increase inhypopharyngeal pressure during swallowing has tobe considered [266]. The lesion, which usually occursin elderly persons, is now widely accepted to be of acquiredrather than congenital origin. The symptomsare virtually pathognomonic: dysphagia, regurgitationof undigested food, weight loss, foetor ex ore, coughingand repeated aspiration [42]. Diagnosis of the diseasemay be confirmed by a barium swallow. Histologically,ZD is composed of a squamous epithelium, thinned fibroustissue of the subepithelial stroma with possibleinflammatory changes. The conservative open surgicalprocedures provide effective results [266]. Exceedinglyrarely, squamous cell carcinoma may develop inZD [42].7.2.7 Aberrant Thyroid TissueFig. 7.2. Oncocytic cyst of the ventricular cord. Cyst is lined withoncocytic epitheliuma diffuse involvement as oncocytic cystadenomatosis isexceptional [230].Histologically, the epithelium of an OC shows papillaryproliferations or a different degree of folding ofthe cystic wall. The epithelium is typically double layered;the inner layer consists of columnar eosinophiliccells encircling the cystic lumina, while the outer layeris composed of small basal cells (Fig. 7.2) . Complete endoscopicalsurgical excision is the recommended treatment,if necessary by laryngofissure [216].7.2.6 Zenker’sHypopharyngeal DiverticleThyroid tissue rarely appears in sites outside of itsembryonic development. The subglottic area of thelarynx and upper trachea are places where aberrantthyroid tissue (ATT) may be found [36], especiallybetween the lower border of the cricoid cartilage andthe upper ring of the trachea. According to differentreports, intraluminal thyroid tissue occurs anywherebetween the glottis and the bifurcation of the trachea,as a broad-based, smooth, rounded mass protrudingfrom the left subglottic posterolateral wall [305, 345].It has been pointed out that two-thirds of patients aremiddle-aged women from regions of endemic goitre[22, 36]. Intralaryngotracheal thyroid is a rare lesion.Only about 125 cases were described up to 1998 [327].Waggoner divided intralaryngotracheal thyroid tissueinto “false” and “true” aberrant thyroids. The formeris likely to arise in the pre- or neonatal period,when the thyroid gland could grow into incompletelyformed laryngotracheal cartilages that remain in continuitywith the thyroid gland. The latter, the “trueaberrant thyroid”, develops during the foetal periodas an isolated, misplaced thyroid tissue, when the thyroidgland is encroached upon and divided by the laterdeveloped laryngeal and tracheal cartilages [327, 361,372]. The most common symptom of intralaryngealATT is slowly progressive dyspnoea, but it may be alsoasymptomatic [278].Histologically, the thyroid follicles are usually small,regular, with a well-formed colloid lying close to the seromucinousglands in the laryngeal mucosa [238]. Theoverlying mucosa is commonly intact, and there may besome evidence of chronic irritation. The finding of thyroidtissue in the laryngotracheal wall raises the questionas to whether or not it represents ectopic tissue appearingthrough a developmental defect or a well-differentiatedcarcinoma. The final decision must be based onan overall clinical evaluation and not only on histologicalfindings [36, 327]. Management of ATT is often notclear-cut, but is proposed to be primarily surgical [327,345, 372].