Pathology of the Head and Neck

264 M. A Luna · K. Pineda-Daboin9.1 IntroductionThe neck connects the organs of the head with those ofthe thorax. It contains important anatomic structures,including blood and lymphatic vessels, nerves and paraganglia,muscles and vertebrae, and numerous lymphnodes, in addition to parenchymatous glands, salivary,thyroid, and parathyroid. The neck also contains organsof the upper aerodigestive tract: larynx, hypopharynxand segments of the oesophagus and trachea.The fact that a neck mass can originate in any of thecervical structures means that a host of disorders challengesthe diagnostic ability of the surgical pathologist.The differential diagnosis of a neck mass includes developmental,inflammatory, benign and malignant neoplasticlesions. The purpose of this chapter is to reviewthe pathology and diagnosis of cervical cysts. Occultprimary tumours of the neck and neck dissection alsoare discussed.99.2 Anatomy9.2.1 Trianglesof the NeckIt is customary to divide the neck into two large triangles,the anterior cervical triangle and the posteriorcervical triangle. The anterior triangle is bounded bythe midline of the neck, the anterior border of the sternocleidomastoidmuscle, and the inferior border of themandible. The posterior triangle is bounded by the anteriormargin of the trapezius muscle, the posterior borderof the sternocleidomastoid muscle and the clavicle.The anterior cervical triangle can be further subdividedinto four lesser triangles (submental, submandibular,superior carotid and inferior carotid) and the posteriortriangle into two (occipital and supraclavicular)the boundaries of which are described in greater detailin other sources [12].9.2.2 Lymph Node Regionsof the NeckThe cervical lymph nodes can be divided into superficialand deep nodes, and each of these groups into lateraland medial. The deep lateral nodes are distributedamong several large groups:1. The submental and submandibular group;2. The internal jugular chain (superior, middle, and inferior);3. The spinal accessory nerves chain;4. The supraclavicular node chain.Fig. 9.1. Cervical nodes by levels and sublevels: IA submental,IB submandibular, II upper jugular, IIA jugulogastric, IIB supraspinalaccessory, III middle jugular, IV lower jugular, V Posteriorcervical, VA spinal accessory nerve nodes, VB transverse cervicalnodes, SC supraclavicular, VI anterior groupThe deep medial cervical group consists of the prelaryngeal,prethyroidal, pretracheal and paratracheal lymphnodes. The superficial medial lymph nodes are distributedaround the anterior jugular vein. The superficiallateral cervical nodes are located along the externaljugular vein.Figure 9. 1 shows the system for describing the locationof lymph nodes in the neck, and used the levels recommendedby the Committee for Head and Neck Surgeryand Oncology of the American Academy for Otolaryngology-Headand Neck Surgery [99].9.3 Cystsof the NeckCysts of the neck are pathological cavities lined withepithelium. The type of epithelium varies, and the cavitymay contain fluid, keratin, mucus or other products.Cervical cysts can be divided into two large groups: developmentaland non-developmental. Establishing theprecise nature of these cysts is important because thereare considerable differences in their biological and clini-