Chapter 6 Nasopharynx and Waldeyer’s Ring 6 S. Regauer Contents 6.1 Embryological Development 6.2.6.2 Papillary Adenocarcinoma of the Nasopharynx and Waldeyer’s Ring . 172 of the Nasopharynx . 182 6.2.7 Malignant Non-Epithelial Tumours 6.2 Nasopharynx . 173 of the Nasopharynx . 183 6.2.1 Anatomy and Histology . 173 6.2.7.1 Chordoma . 183 6.2.2 Congenital Developmental Anomalies . 173 6.2.7.2 Sarcoma . 183 6.2.2.1 Nasopharyngeal Branchial Cleft Cysts . 173 6.2.2.2 Tornwaldt’s Cyst . 173 6.3 Waldeyer’s Ring . 183 6.2.2.3 Rathke’s Cleft Cyst/Ectopic Pituitary Tissue . 174 6.3.1 Anatomy and Histology of Waldeyer’s Ring . 183 6.2.2.4 Craniopharyngioma . 174 6.3.2 Congenital Anomalies of Waldeyer’s Ring . 184 6.2.2.5 Heterotopic Brain Tissue/Encephalocele . 174 6.3.3 Tonsillitis . 184 6.2.3 Congenital Tumours . 174 6.3.3.1 Bacterial Tonsillitis . 184 6.2.3.1 Salivary Gland Anlage Tumour . 175 6.3.3.2 Viral Tonsillitis . 185 6.2.3.2 Hairy Polyp . 175 6.3.4 Benign Tumours of Waldeyer’s Ring . 187 6.2.3.3 Congenital Nasopharyngeal Teratoma . 175 6.3.4.1 Squamous Papilloma . 187 6.2.4 Benign Tumours and Tumour-Like Lesions . 175 6.3.4.2 Lymphangiomatous Tonsillar Polyp . 187 6.2.4.1 Nasopharyngeal Angiofi broma . 175 6.3.5 Carcinomas of Waldeyer’s Ring . 187 6.2.4.2 Respiratory Epithelial 6.3.6 Malignant Lymphomas of Waldeyer’s Ring . 189 Adenomatoid Hamartoma . 178 6.3.6.1 Mantle Cell Lymphoma . 189 6.2.4.3 Nasopharyngeal Inverted Papilloma . 178 6.3.6.2 Extranodal Marginal Zone B-Cell Lymphoma 6.2.4.4 Solitary Fibrous Tumour . 179 of Mucosa-Associated Lymphoid Tissue . 190 6.2.4.5 Paraganglioma . 179 6.3.6.3 Extranodal NK/T-Cell Lymphoma, 6.2.4.6 Meningioma . 179 Nasal Type . 190 6.2.4.7 Glandular Retention Cysts . 179 6.3.6.4 Hodgkin’s Lymphoma . 190 6.2.5 Nasopharyngeal Carcinoma . 180 6.3.6.5 Extramedullary Plasmacytoma . 190 6.2.5.1 Non-Keratinising Nasopharyngeal 6.3.7 Systemic Disease Aff ecting Waldeyer’s Ring . 190 Carcinoma . 180 References . 191 6.2.5.2 Keratinising Nasopharyngeal Carcinoma . 182 6.2.6 Nasopharyngeal Adenocarcinoma . 182 6.2.6.1 Salivary Gland-Type Adenocarcinoma of the Nasopharynx . 182 172 S. Regauer 6.1 Embryological Development al bursa in adults is located at the posterior median wall of the Nasopharynx of the nasopharynx above the superior pharyngeal con- and Waldeyer’s Ring strictor muscles at the lower end of the pharyngeal ton- sil and is known as Tornwaldt’s cyst (see Sect. 6.2.2.2). The pharynx is divided into an upper portion, the na- Remnants of the notochord give rise to cranial chordo- sopharynx, and a lower portion consisting of the oro- mas (see Sect. 6.2.7.1). pharynx and hypopharynx. The nasopharynx is located The oropharynx, mouth and larynx develop from above the soft palate and communicates with the nasal the pharyngeal (or branchial) apparatus during the passages. The oropharynx extends from the soft pal- 4th and 5th weeks of gestation. The growth of the fore- ate and the velum palatinum to the epiglottis. The hy- brain and the development of the pharyngeal/bran- popharynx extends from the tip of the epiglottis to the chial apparatus produce a prominent elevation of the lower margin of the cricoid cartilage. The term Waldey- head with a quite distinct first and second pharynge- er’s ring refers to the ring of lymphoid tissues extending al arch around day 24. At the end of the 4th embryonic 6 throughout the naso- and oropharynx and includes the week, four well-defined and two rudimentary bilateral palatine, pharyngeal, lingual and tubal tonsils. pairs of pharyngeal arches are separated by the pharyn- The earliest embryological stage relevant for the de- geal grooves. Each arch consists of a core of embryon- velopment of the nasopharynx is around the 3rd week of ic mesenchyme with an artery, a cartilage rod, a nerve gestation. The embryo has already developed all three and a muscular component, and is covered externally germ layers and consists of the notochord with a noto- by ectoderm and internally by endoderm. The ectoder- chordal lumen [134]. At the cranial end, the notochord mally derived pharyngeal arches and grooves support is still fused with the ecto- and endodermal germ layers, the lateral walls of the primitive pharynx. The inner which form the bilaminar oropharyngeal (or buccopha- lining consists of endoderm with balloon-like diver- ryngeal) membrane. The first process in the formation ticuli called pharyngeal pouches, which are also pres- of the pharynx is the development of a primitive mouth ent in four well-defined pairs. The second pharynge- (or stomodeum) and a primitive pharynx during the 4th al pouch is the major contributor to the formation of week via rupture of the oropharyngeal membrane. At the pharynx and is largely obliterated when the pala- that time, the primitive nasal cavities and the nasophar- tine tonsils develop around weeks 12–14 post-concep- ynx are still separated from the oral cavity by the pri- tion. A part of the cavity of the second pouch remains mary palate and the oronasal membrane. The oronasal as the intratonsillar cleft (or tonsillar fossa) in the pal- membrane ruptures around week 6, bringing the nasal atine tonsils (see Sect. 6.3.1). The neural crest-derived and oral cavity into continuity and forming the primi- mesenchyme will form most of the skeletal (cartilage tive choanae. During the posterior extension of the pri- and bone) and connective tissue structure of the head mary palate and development of the secondary palate, and neck, but the original mesenchyme of the second the choanae become located posteriorly and connect the arch forms the blood vessels and skeletal musculature newly formed nasal cavities and nasopharynx. The de- of the pharynx. The nerve supply of the pharynx devel- velopment of the pituitary gland (or hypophysis) begins ops from the 3rd pharyngeal arch (IX glossopharyn- around the middle of the 4th week with an upward pro- geal nerve). The adult vascular pattern of the head and liferation of the ectodermal roof of the stomodeum, the neck depends on a complex transformation of the pha- Rathke’s pouch (or hypophyseal duct), and a downgrowth ryngeal apparatus with involution and obliteration of from the diencephalon called the neurohypophyseal bud. the early vessels. Incomplete involution, particularly The Rathke’s pouch passes through the chondrification of the first pharyngeal artery, has been postulated to centres of the developing sphenoid bones. By the 5th be responsible for the development of nasopharyngeal week, both portions of the pituitary gland have come in angiofibromas (see Sect. 6.2.4.1). The auditory (Eusta- contact and the Rathke’s pouch becomes constricted at chian) tube is derived from the first pharyngeal arch its attachment to the oronasal epithelium. The stalk de- and pouch. Incomplete regression may be responsible generates and the Rathke’s pouch involutes to a series of for the occurrence of hairy polyps (see Sect. 6.2.3.2). microcysts, which persist throughout adult life in the pi- The tongue also begins to develop at the end of the 4th tuitary gland. Occasionally, they can be recognised mac- week. The oral part of the tongue is derived from the roscopically by a zone of colloid cysts. Symptomatic en- first pharyngeal arch; the posterior pharyngeal tongue largement leads to the formation of a Rathke’s cleft cyst develops by fusion of the ventromedial parts of the sec- (see Sect. 6.2.2.3). Around the same time, during the in- ond and the third pharyngeal arch. The tissues derived volution of the notochord, a pharyngeal bursa is formed from the second pharyngeal arch are gradually over- temporarily at the site of early communication between grown by the third pharyngeal arch. the notochord and the roof of the pharynx. This ecto- The lymphoid tissues of Waldeyer’s ring develop be- dermally derived pharyngeal bursa normally obliterates tween the 14th and 18th weeks of gestation. The devel- during the 6th gestational week. A persistent pharynge- opment of the pharyngeal tonsil begins from an anlage Nasopharynx and Waldeyer’s Ring Chapter 6 173 consisting of longitudinal folds on the dorsal wall of the der associated with sleep apnoea and other craniofacial nasopharynx around the 12–14th gestational week. The anomalies [108, 137]. Far more common are congenital development of the palatine tonsils begins with a prolif- cysts and tumours arising from remnants of embryonic eration of the endodermal epithelium of the second pha- tissue. ryngeal pouch down into the surrounding mesenchyme, forming the epithelium-lined crypts. In the connec- tive tissue, mesenchymal cells of the second pharynge- 6.2.2.1 Nasopharyngeal al pouch form so-called condensation centres. The first Branchial Cleft Cysts primary follicles can be localised around week 14. The parafollicular areas develop into T-cell areas and pre- Nasopharyngeal branchial cleft cysts and fistulas are cursors of interdigitating cells can be identified. Around located in the lateral nasopharyngeal wall and can ex- week 16, the epithelium shows the first signs of cornifi- tend to the base of the skull through the parapharyngeal cation, and the lymphocytic infiltration of the epitheli- space. They occur unilaterally or bilaterally and have a um occurs [59, 60]. postulated second pharyngeal arch origin. Most naso- pharyngeal branchial cleft cysts are clinically silent dur- ing childhood and discovery may be delayed into early 6.2 Nasopharynx adulthood, when chronic inflammation induces prolif- eration of the lymphoid tissues.