As explained in Chap.​ 1, the human branchial apparatus is formed by pharyngeal pouches (endoderm), arches (mesoderm), and clefts (ectoderm). The branchial apparatus, in continuity with the embryonic foregut form the adult pharynx. Contributions of these multiple structures are shown in Table 11.1 [1, 2].

The most common congenital anomalies of the neck are those derived from the thyroglossal duct (70 %), followed by anomalies of the branchial apparatus (30 %) [3, 4]. Thyroglossal duct cysts most often present as midline cervical masses located anywhere between the base of the tongue and the sternal notch. The tract most often goes through the body of the hyoid bone. While originally sterile, communication of the cyst with the pharynx through the foramen cecum and thyroglossal duct may predispose the cyst to infection. There is a small reported incidence of malignancy in this ectopic tissue (1 %), with papillary thyroid cancer being the most common type and a medullary carcinoma being embryologically impossible.

Thyroglossal duct cysts must be distinguished from the other two midline neck masses, which are dermoid cysts and the Delphian lymph node. This can be done on clinical grounds. Thyroglossal cysts move with swallowing but more importantly move superiorly with protrusion of the tongue. Dermoid cysts arise from the skin and hence move with the skin. The Delphian node is a lymph node draining the thyroid gland.

Considering that the thyroglossal duct does not communicate with the skin, it is thought that thyroglossal sinuses and fistula are not congenital, but rather represent secondary drainage of a cyst or abscess [5] (Fig. 11.1).

The presence of a lingual thyroid should raise a strong suspicion of the absence of additional thyroid tissue in the neck. Considering this, removal of lingual thyroid must be preceded by a thyroid scan. Lingual thyroid glands have no embryologic relation to mediastinal thyroid tissue. The former occur due to failure of descent of the thyroglossal duct that normally forms the medial thyroid anlagen. The latter is derived from anomalous decent of the lateral thyroid anlagen, derived from the fourth pharyngeal pouch.

Branchial anomalies may present as cysts, sinuses, or pharyngocutaneous fistulas (Table 11.2). The level at which these anomalies are located along the neck depends on their embryologic origin; however, all of them are anterior to the sternocleidomastoid muscle. The second arch is most commonly affected (95 % of cases). The definitive treatment of all branchial anomalies is complete excision [6, 7]. Choanal atresia results from the persistence of the nasobuccal membrane. When bilateral, infants present with apnea during quiet respiration, which is relieved during crying. This is due to the fact that neonates are nasal breathers during the first 6 weeks of life, but become mouth breathers while crying. In addition, those affected have copious nasal secretions. Treatment involves securing the airway through intubation followed by surgical repair or tracheostomy if repair is not possible. Choanal atresia is part of the CHARGE syndrome, composed of coloboma, heart defects, choanal atresia, developmental retardation, genitourinary anomalies, and ear abnormalities [8].

Zenker’s diverticulum consists of a protrusion of pharyngoesophageal mucosa through Killian’s triangle, a weak area above the superior esophageal sphincter (cricopharyngeus muscle). It is thought that Zenker’s diverticulum arises due to the presence of a hypertonic cricopharyngeus resulting in increased pharyngeal swallowing pressures. This leads to the formation of a false (pulsion) diverticulum that most often lies in the left neck. Due to its lack of musculature, Zenker’s diverticulum is unable to empty, collecting food particles causing reflux, aspiration, and severe halitosis [9, 10]. In view of the above-described pathophysiology, the key step in management consists of division of the cricopharyngeus muscle. The state of cricopharyngeus spasm has been attributed to gastroesophageal reflux. The initial test of choice to diagnose this condition is a barium esophagogram (Fig. 11.2).

Tonsil and adenoid enlargement are a common benign finding, especially in the pediatric population. However, occasionally occult malignancies (most often lymphoma and lymphosarcoma) may be present. While the prevalence of this finding is rare, special care should be taken when assessing older patients with tonsillar asymmetry and associated lymphadenopathy [11]. Ear pain in the absence of ear pathology may be due to tumor involvement of the Eustachian tubes. Similarly, the presence of enlarged upper cervical lymph nodes may be the consequence of metastatic spread of tonsillar carcinomas.

Juvenile nasopharyngeal angiofibromas are rare extremely vascular tumors seen almost exclusively in adolescent males. Their vascular nature preludes biopsy. While initially slow growing, they eventually invade the base of the skull and may cause significant bleeding. Traditionally, treatment has consisted of surgical resection following angiographic embolization [12].

Craniopharyngiomas are benign tumors arising from Rathke’s pouch, the endodermal precursor to the anterior pituitary. While benign in nature, their treatment is difficult due to proximity with critical structures as well as their tendency to recur [13, 14].

Nasopharyngeal bursa or Thornwaldt’s bursa is a notochord-derived recess in the posterior nasopharynx. Obstruction of its draining orifice may lead to cyst formation, resulting in nasal obstruction [15].

Kursteiner cysts are an anatomic variation of the parathyroid glands. They may be lined with differentiated parathyroid cells producing PTH.

Cleft palate results from the failed fusion of the maxillary prominences derived from the first pharyngeal arch and the middle nasal prominence. Difficulty in generation of negative intraoral pressures may lead to failure to thrive. The abnormal insertion of the tensor veli palatini (which acts as a sphincter to the pharyngeal opening of the Eustachian tube) predisposes to middle ear disease and conductive hearing loss [16].

Palatine tonsils are often inflamed due to self-limited viral and bacterial infections. However, these benign infections may progress to abscess formation, affecting the peritonsillar or parapharyngeal spaces, causing systemic septic symptoms as well as trismus [17].

Hypoglossal nerve injury is the most common nerve injury during carotid endarterectomy, and it is seen in approximately 2 % of cases, with higher rates being reported in the face of prior radiation or surgery. Interestingly, this condition constituted selection criteria for carotid stenting in the SAPPHIRE trial [18, 19]. Laryngeal clicking is a normal physical finding elicited by displacing the larynx laterally over the cervical spine. The loss of this finding has been associated to retrolaryngeal masses as well as to traumatic retrolaryngeal edema [20].

Treatment of cancers of the base of the tongue has shifted from radical resections to neoadjuvant chemoradiation coupled with organ-preserving surgery. The rich lymphatic drainage of the tongue determines that metastatic nodal involvement is often bilateral. This makes bilateral neck dissection necessary in patients with multiple nodal involvement [21].

The surgical treatment of obstructive sleep apnea is usually reserved for patients who have failed treatment with positive airway pressure. While excision of redundant oropharyngeal tissue (veloplasty and uvuloplasty) is an important treatment principle, other strategies include improving nasal airflow through septoplasty or turbinectomy and mobilizing the tongue anteriorly, either through genioglossus advancement or en bloc with the mandible through osseous distraction of the jaw [22].

Barrett’s esophagus represents an instance of metaplasia, in which a mature epithelium is replaced by another kind of mature epithelium due to environmental stresses. In the esophagus, the normal squamous epithelium is replaced by intestinal-like columnar epithelium. While the change in epithelial phenotype is reversible, it is a first step in the development of cancer. Dysplasia refers to a loss in the degree of cellular differentiation within a given tissue, leading to the replacement of fully differentiated cells by abnormal cells with altered microarchitecture. Anaplasia characterizes fully transformed cells and consists in the complete loss of cellular differentiation typical of cancer.