Nasopharynx

The nasopharynx is broadly defined as that area of the mucosal surface that encompasses the superior, lateral, and posterior walls of the aerodigestive tract, above the soft and hard palate, extending to the skull base. Below the nasopharynx lies the oral cavity anteriorly and the oropharynx posteriorly. The nasopharynx is lined by stratified squamous and ciliated columnar epithelium and includes the mucosa overlying the eustachian tube orifice, the cartilaginous portion of the eustachian tube (torus tubarius), and the posterolateral pharyngeal recesses known as the fossa of Rosenmüller (Fig. 14-1). The mucosa of the nasopharynx is separated from the deeper retropharyngeal space by the pharyngobasilar fascia. The pharyngobasilar fascia forms a rather stiff barrier to the spread of mucosal diseases, but it has bilateral openings, the sinus of Morgagni, to emit the eustachian tubes. The buccopharyngeal fascia is deep to the pharyngobasilar fascia and serves as another of the fascial barriers from nasopharynx to retropharyngeal and parapharyngeal spaces.

Figure 14-1 Normal nasopharyngeal anatomy. The torus tubarius (white arrow), eustachian tube orifice (open white arrow), and fossa of Rosenmüller (asterisk) are labeled. The tensor veli palatini (black arrow) and levator veli palatini (+) are seen. A midline pit (squiggly arrow) may be due to early Tornwaldt cyst formation.

On either side of the eustachian tube orifice lie, anterolaterally, the tensor veli palatini muscle (innervated by cranial nerve V-3) and posteromedially the levator veli palatini muscle (innervated by cranial nerve X), deep to the mucosa (see Fig. 14-1). These muscles elevate and tense the soft palate, into which they insert, preventing nasal regurgitation during swallowing. Between these muscles is a slip of fat (typically obliterated in early nasopharyngeal carcinomas), and posterolateral to these muscles lies the fat-filled parapharyngeal space. Fixate on fat—an effective friend for finding pharyngeal foulness.

The nasopharynx also houses the adenoidal lymphoid tissue. The amount of adenoidal tissue present depends on the age of the patient, because it atrophies by the fourth decade of life. In a young adult the normal adenoidal tissue or lymphoid hyperplasia may simulate a lymphoma or an exophytic squamous cell carcinoma. In human immunodeficiency virus (HIV)-positive patients, on average, the width of the adenoidal tissue is twice that of age-matched controls (Fig. 14-2). The normal variation in adenoidal thickness requires vigilance for deep invasion, infiltration of the parapharyngeal fat, concomitant middle ear or mastoid opacification, skull base erosion, or obscuration of the planes between the tensor and levator veli palatini muscles to definitively suggest carcinoma. Lymphoid tissue here and in the palatine and lingual tonsils is usually slightly hyperintense on T1-weighted images (T1WI) and hyperintense on T2-weighted images (T2WI) and enhances. These imaging characteristics would be unusual for a squamous cell carcinoma but could occur in a lymphoma. The adenoids, the palatine (also known as faucial) tonsils, and the lingual tonsils make up Waldeyer’s ring of lymphoid tissue (Fig. 14-3). All of these regions may show lymphoid hyperplasia in cases of HIV infection and mononucleosis or because of exposure to chronic irritants (cigarette smoke, alcohol, and chewing tobacco).

Figure 14-2 Adenoidal hypertrophy. The width of the nasopharyngeal adenoid tissue (asterisk) is enlarged in patients with human immunodeficiency virus (HIV) infection and is one of the findings to check for on sagittal T1-weighted scans of the brain. Diminished marrow signal intensity, posterior triangle nodes, and parotid cysts may be other signs of early HIV.

Figure 14-3 Waldeyer’s ring. The adenoids and lingual tonsils are basically midline structures, whereas the palatine tonsils are found bilaterally framed by the pharyngeal faucial arches. These arches are created by the palatoglossus (anteriorly) and palatopharyngeus (posteriorly) muscles.

Minor salivary gland tissue is present throughout the aerodigestive system and is relatively abundant in the nasopharynx, oropharynx, and oral cavity. The hard and soft palate has the highest concentration of minor salivary glands (and consequently the highest rates of minor salivary gland neoplasms). Squamous epithelium lines the vast majority of the aerodigestive system mucosa of the head and neck.

Oropharynx

The oropharynx includes the posterior third of the tongue (also known as the tongue base), the vallecula, the palatine tonsils and tonsillar fossa, the posterior and superior pharyngeal walls from the level of the soft palate down to the pharyngoepiglottic folds, the uvula, and the soft palate (Fig. 14-4). The circumvallate papillae of the tongue separate the oral tongue (a part of the oral cavity) anteriorly from the oropharynx posteriorly. The hard palate is part of the oral cavity, but the soft palate is part of the oropharynx. Besides the palatine tonsils, the oropharynx also contains the lingual tonsillar tissue seen at the base of the tongue.

Figure 14-4 Normal anatomy of the oropharynx. On this axial T1-weighted image one can identify the base of the tongue with lingual tonsil tissue (small arrows) and the palatine tonsils (t). Also identifiable on this scan are the submandibular glands (g), the sublingual space extending from the submandibular glands anteriorly, and the midline fatty lingual septum with genioglossus muscles on either side. Muscles on either side of the sublingual space are the mylohyoid muscles (m) laterally and the hyoglossus (asterisk) medially. Geniohyoid muscle (gh) makes up the bulk of the tissue anteriorly in the tongue, usually below genioglossus.

Oral Cavity

The oral cavity includes the lips, the anterior two thirds of the tongue, the buccal mucosa, the gingiva, the hard palate, the retromolar trigone, and the floor of the mouth. The circumvallate papillae separating the oral tongue from the base of the tongue and the hard palate-soft palate junction function as boundary zones between the oral cavity and oropharynx.

For the radiologist the phrase “the floor of the mouth” should be equated with the mylohyoid musculature (which constitutes the inferior sling of the mouth) and the sublingual space, between the mylohyoid muscle and the hyoglossus muscle (Fig. 14-5). The lingual nerve from the trigeminal nerve and the hypoglossal nerve run together from the floor of the mouth into the tongue base and sublingual space and are important for the surgeon to identify and retain to maintain tongue function. Radiologists must identify whether tumor is in the sublingual space to alert the surgeon regarding the potential for invasion or sacrifice of these nerves. The chorda tympani from the facial nerve supplies taste to the anterior two thirds of the tongue, and its branches join those of the lingual nerve. The glossopharyngeal nerve supplies taste to the posterior third of the tongue.

Figure 14-5 Normal anatomy of the oral cavity. The hard palate (small arrows), the anterior two thirds of the tongue (t), and the gingival surfaces of the mandible constitute portions of the oral cavity. The oral cavity also includes the floor of the mouth, seen as the mylohyoid (m) muscular sling inferolaterally.

Hypopharynx

The hypopharynx is the junction between pharynx and larynx and includes three major subsites: the piriform sinus, the postcricoid region (pharyngoesophageal junction), and the posterior pharyngeal wall above the inferior border of the cricoid cartilage (Fig. 14-6). The top of the hypopharynx is at the epiglottic level, and its inferior border is the pharyngoesophageal junction. The mucosa over the posterior surface of the cricoarytenoid joints is part of the hypopharynx. The anteromedial border of the piriform sinus is the aryepiglottic fold, a structure of the supraglottic larynx.

Figure 14-6 Anatomy of the hypopharynx. Axial T1-weighted image demonstrates the air-filled piriform sinuses (asterisks), which are delineated anteromedially by the aryepiglottic folds (small arrows). Other subsites of the pharynx in this location include the posterior and lateral pharyngeal walls.

The piriform sinus is best evaluated endoscopically with the patient performing Valsalva maneuver because this distends the airway down to its inferiormost portion, the piriform apex. This maneuver may also be employed during barium studies or ultrafast computed tomography (CT) scans. The apposition of mucosal surfaces in the piriform sinus often makes lesion localization difficult. You may not be able to distinguish extension to the adjacent aryepiglottic fold, the lateral piriform sinus mucosa, or the posteromedial mucosa without such maneuvers to maximize distention.

Larynx

The larynx is broadly separated into the supraglottis, the glottis, and the subglottis (Fig. 14-7). Each of these areas is dealt with individually by the head and neck oncologic surgeon, although lesions often cross these boundaries of the larynx (transglottic cancers). The supraglottis includes the false vocal cords, the arytenoids, the epiglottis, and the aryepiglottic folds. The glottis includes the true vocal cords, the anterior and posterior commissures, and the vocal ligament extending from the arytenoid cartilage. The laryngeal ventricle is said to separate the supraglottis and glottis, but is itself a part of the supraglottis. The subglottis begins 1 cm below the ventricle and extends to the first tracheal ring.

Figure 14-7 Normal laryngeal anatomy. A, Coronal T1-weighted image (T1WI) shows the laryngeal ventricle (••), which separates the false cord above from the true cord below. Note that at the false cord level the paraglottic tissue is high intensity from fat (arrows), whereas below the ventricle the soft tissue is muscular () from the thyroarytenoid muscle, which makes up the bulk of the true cord. One centimeter below the ventricle is the margin of the subglottic region. B, Axial T1WI demonstrates the supraglottic structures, including the aryepiglottic fold (f) extending posteroinferiorly toward the arytenoid region. C, At the false cord level one again can identify the fat (arrows) in the paraglottic space. D, At the true cord level the paraglottic tissue is made up of the thyroarytenoid musculature. The landmark for the true cord level is the cricoarytenoid joint (arrows). E, Subglottic region is marked by the full cricoid (c) ring.

The larynx is anchored on a framework composed of the hyoid bone, the epiglottis, the thyroid cartilage, the cricoid cartilage, and the arytenoids, each of which has an integral function. Of these, the complete ring of the cricoid cartilage is the only indispensable strut for preservation of airway patency. The major role of the epiglottis is to protect the airway during swallowing. From the inferior portion of the arytenoid cartilage the vocal ligament stretches to the thyroid cartilage anteriorly and supports the vocal cord. The lower cricoarytenoid joint is the marker for the level of the true vocal cord (Fig. 14-8). The true vocal cords meet in the midline at the anterior commissure. This junction should be no more than 1 to 2 mm thick. The posterior commissure refers to the mucosa between the two vocal processes on the anterior surface of the arytenoid cartilage.

Figure 14-8 False cord and true cord levels. A, The false cord is characterized by low-density fat (arrows) in the paraglottic space. B, The true cord is located at the lower cricoarytenoid joint (arrows). The thyroarytenoid muscle (+) makes up the “paraglottic” tissue, and this muscle attaches to the vocal process of the arytenoid.

On the lateral side of the laryngeal mucosal surface is the paraglottic space, which contains fat, lymphatics, and small muscles. At the false cord level the paraglottic space contains fat, whereas at the true cord level it contains the thyroarytenoid muscle, another important landmark to define laryngeal levels. Thus, you can tell if you are at a supraglottic level by seeing fat deep to the mucosa—at the glottic level it is muscle that is seen submucosally. The thyroarytenoid muscle makes up the bulk of the true vocal cord and parallels the vocal ligament. The cricoarytenoid muscle moves the arytenoids to narrow or open the glottic airway for speech.

The vagus nerve innervates the larynx through two branches: the recurrent laryngeal nerve and the superior laryngeal nerve. The only muscle supplied by the latter is the cricothyroid muscle, and its paralysis causes only minor changes in the voice. The course of the vagus and recurrent laryngeal nerve is important to understand in patients with vocal cord paralysis. The nerve descends from the medulla through the jugular foramen into the carotid sheath. The vagus follows the carotid sheath inferiorly with the recurrent laryngeal nerve, looping under the aortic arch on the left and the subclavian artery on the right, before ascending in the tracheoesophageal groove. The branches of the recurrent laryngeal nerve perforate the cricothyroid membrane to supply the intrinsic musculature of the larynx.

Lymph Nodes

Although the lymph nodes are not a part of the mucosa of the head and neck, it seems more relevant to discuss the nodes in the chapter dealing with squamous cell carcinoma. The most common cause of nodal disease in an adult is a squamous cell carcinoma metastasis from a mucosal primary tumor.

The nomenclature of the lymph nodes of the neck has undergone a recent change, which is supported by various societies of head and neck surgeons. This nomenclature identifies the lymph nodes by a grading system from I to VII (Fig. 14-9). Level I lymph nodes include the submental (IA) and submandibular (IB) lymph node chains. Level II lymph nodes include the internal jugular lymph node chain above the hyoid bone, which are anterior or immediately adjacent to the jugular vein (IIA) or posterior to the jugular vein deep to the sternocleidomastoid muscle (IIB). The level IIA nodes include the jugulodigastric node, a node that sits along the posterior belly of the digastric muscle at the upper pharyngeal level. Level III lymph nodes involve the jugular chain between the hyoid and cricoid cartilage, and level IV lymph nodes involve the jugular chain below the cricoid cartilage. Level V is designated as all the lymph nodes of the posterior triangle of the neck (deep and posterior to the sternocleidomastoid muscle and above the clavicle). If above the cricoids, they are designated VA; if below, VB. Level VI lymph nodes are those that previously were identified in the anterior jugular and visceral chain in front of the thyroid gland. Finally, level VII nodes are in the superior mediastinum region.

Figure 14-9 Nodal classification. The revised nodal classification scheme includes and A and B designation for nodes in levels I, II and V. IA refers to submental and IB to submandibular nodes. In II the separation depends on the relationship to the carotid sheath/jugular vein, with IIA anterior or along and IIB posterior, but both above the hyoid bone, as opposed to level III nodes between hyoid and cricoid cartilage. With the posterior triangle classification V, the upper nodes above the cricoid cartilage are designated VA and the lower ones are VB.

Branchial Apparatus Fistulae

Branchial cleft cysts (BCCs) are not considered to be “mucosal lesions” so they are discussed in Chapter 15. However, when they drain to the mucosal surface, they may present as such. Second branchial cleft fistulae may drain to the palatine tonsil from their typical location deep to the sternocleidomastoid muscle but superficial to the carotid sheath (Bailey type II, second BCC). Those arising in the parapharyngeal space and potentially draining to the mucosa are classified as Bailey type IV, second BCC.

The piriform sinus is a drainage site for third BCCs, and the piriform sinus apex may be a site of sinus tracts leading from fourth BCCs (see Table 15-2 and Fig. 15-59). The third branchial cleft sinus tract passes between the common carotid artery and vagus nerve to the anterior border of the inferior sternocleidomastoid muscle. The fourth branchial cleft sinus tract passes around the great vessels and the aortic arch on the left side. Piriform sinus fistulae from the fourth branchial apparatus may pass to the thyroid gland, causing acute suppurative thyroiditis or open to the skin. The vast majority of these fistulae are left sided. Recurrence rates are about 40%. Most occur in children.

Capillary Hemangioma

When subglottic narrowing is seen in an infant, the differential diagnosis is usually between a capillary hemangioma and idiopathic subglottic stenosis. The subglottic capillary hemangioma is a benign neoplasm that generally occurs in 1- to 2-year-olds. Fifty percent of patients with subglottic hemangiomas have cutaneous hemangiomas as well. This is a benign tumor that often responds to steroid therapy, benign neglect (because it regresses with age), or laser therapy. In general, excisional treatment is not required except in those cases where extensive laryngeal narrowing is produced by the mass. On plain films the subglottic hemangioma causes an asymmetric narrowing of the airway of the subglottis. CT and MR reveal a smooth, enhancing mass that is asymmetric in the subglottis and that compromises the airway. In adults hemangiomas are usually supraglottic lesions. Capillary hemangiomata and idiopathic subglottic stenosis are benign entities, and the infant may outgrow the lesions if supportive care is provided. Subglottic stenosis may also occur from previous intubation or as a result of previous inflammatory disease in this region of the larynx. Webs may occur at the true cord level.

Cephaloceles

Transsphenoidal encephaloceles may present as a nasopharyngeal mass. Usually the endoscopist is able to identify dura, dural blood vessels, or pulsating brain tissue. This entity is seen most commonly in Southeast Asians (see Fig. 9-19). Encephaloceles often include unexpected anatomy of intracranial origin. Teratomas tend to transgress transsphenoidally too and transmit totipotential, “toti-intensity” tissue.

The craniopharyngeal canal is the route by which the anterior pituitary gland ascends from the pharynx to the pituitary fossa. Nasopharyngeal craniopharyngiomas are very uncommon but represent neoplasms related to the craniopharyngeal duct that ascends from the pharynx to the suprasellar region. They are mentioned here in the congenital section for confusion purposes and also in Chapter 11.

Developmental Inclusion Cysts

Epidermoids and less commonly dermoids and lymphangiomas (usually multilocular) may occur in the tongue, usually in its oral portion. The dermoids contain fat or fluid and are usually in the floor of the mouth. Epidermoid cysts usually occur in the sublingual space and have fluid density and signal intensity (Fig. 14-10). The lesion may have geometric designs within the cyst.

Figure 14-10 (Epi)dermoid cyst of tongue. A, Axial T2-weighted image (T2WI) is dominated by the very bright midline mass in the oral tongue. It is too anterior to be a thyroglossal duct cyst and not lateral or inferior enough to be a ranula. B, The sagittal postcontrast T1WI confirms the cystic nature of the mass by virtue of the absence of enhancement.

Of the congenital cysts in the maxilla, the nasopalatine cyst (incisive canal cyst) is the most common. This cyst usually arises in the midline incisive canal and slowly expands the maxilla and hard palate. Usually the cyst is painless and the teeth are unaffected. Therefore, it is not considered an odontogenic cyst.

Cherubism

Cherubism can occur in patients with familial fibrous dysplasia of the mandible, neurofibromatosis, Noonan syndrome (male Turner syndrome), and Ramon syndrome (cherubism, gingival fibromatosis, epilepsy, and mental retardation). The ground-glass appearance and “bubbliness” akin to fibrous dysplasia are typical of this bilateral bony lesion.

Lingual Thyroid Gland

Thyroid tissue may be seen embedded in the posterior tongue because of arrested descent from the foramen cecum, which is located at the junction of the two sides of the circumvallate papillae along the anterior edge of the base of the tongue. This thyroid tissue is typically in the midline, hyperdense on noncontrast CT because of its natural iodine content, and enhancing. After identifying the lingual thyroid tissue, the radiologist must next image the neck for any additional thyroid gland residua (Fig. 14-11). In 80% of cases the lingual thyroid tissue is the only functioning thyroid tissue in the body. Although treatment is excisional due to a risk of airway compromise in adolescence, the surgeon may elect to leave a little length of lasting lingual thyroid in place if this is the case. Incomplete descent of the thyroid gland to its normal location in the lower part of the neck is an uncommon congenital anomaly.

Figure 14-11 Lingual thyroid. Sagittal T2-weighted image shows a mass at the base of the tongue (arrows) that is low in signal intensity. This would be unusual for lingual tonsillar hypertrophy.

(Courtesy of Suresh Mukherji, University of Michigan Medical Center.)

Lymphatic Vascular Malformations

Congenital lymphatic lesions of the head and neck (in decreasing size) include cystic hygromas, cavernous lymphangiomas, and capillary lymphangiomas. Most cystic hygromas are apparent at birth (50% to 60%) and are seen most commonly in the neck (75%) and axilla (20%) (Fig. 14-12). Cystic hygromas may transilluminate. Occasionally, they may be diagnosed in utero because of polyhydramnios. They are usually hypodense and multiloculated on CT and have variable intensity on T1WI and T2WI because of their potential for proteinaceous-chylous-hemorrhagic content. The mass may present acutely as a result of spontaneous or posttraumatic intralesional hemorrhage with fluid-fluid levels or infection. The cystic hygroma is not invasive but is infiltrative, being compressible and distorted by arteries. The cause of these lesions is thought to be obstruction of the primitive lymphatic channels that are derived from the venous system early in gestation. An association with Turner syndrome, Noonan syndrome, and fetal alcohol syndrome is well-described.

Figure 14-12 Cystic hygroma. What is bright on a T1-weighted image (T1WI) (A), intensely bright on a T2WI (B), nonenhancing, multiloculated, and located in the posterior triangle of the neck in a child? Cystic hygroma.

Stenoses of the Airway

Narrowings of the oropharynx can cause or be a result of obstructive sleep apnea and the Pickwickian syndrome (morbid obesity, hypoventilation, and polycythemia). The narrowing of the airway may be due to obesity, redundancy of mucosal and muscular tissue, or hypertrophy of lymphoid tissue, or it may have a congenital basis (hence discussed herein). In general cross-sectional diameters of the oropharynx are reduced in patients with obstructive sleep apnea at the soft palate, base of tongue, or uvula levels. The normal cross-sectional airway measurement should be about 100 mm². Patients with obstructive sleep apnea often have values at or below a width of 50 mm² and may correspond with oxygen desaturation episodes. Treatment options for obstructive sleep apnea are varied and include behavioral modification, such as weight reduction, sleep hygiene, intraoral appliances that advance the mandible, positional training, and continuous positive airway pressure applied via a nasal mask. Uvulopalatopharyngoplasty or other surgical interventions are reserved for those who fail conservative therapy and who experience significant deoxygenation/hypoxia in their sleep.

Thyroglossal Duct Cysts

Thyroglossal duct cysts (TGDCs) may also occur in the tongue base or floor of mouth. TGDCs are much more common entities than lingual thyroid glands but are usually infrahyoidal. This entity is covered in the thyroid gland section of Chapter 15.

Tornwaldt Cyst

The most common congenital lesion of the nasopharynx (and by the way, of the head and neck) is the Tornwaldt cyst (Fig. 14-13). This results from apposition of the mucosal surfaces of the nasopharynx in the midline as the notochord ascends through the clivus to create the neural plate. A Tornwaldt cyst usually is hypodense on CT. The intensity on magnetic resonance (MR) imaging varies with the protein content but is usually bright on T1WI and T2WI. The cyst is usually well-defined and characteristically occurs in the midline, although it may be seen off-midline in a small percentage of cases. The cysts become infected on rare occasions and may be a source of persistent halitosis.

Figure 14-13 Tornwaldt cyst. A, Sagittal T1-weighted image (T1WI) demonstrates a hyperintense mass (t) high in the nasopharynx. B, On T2WI the mass is seen to be just off-midline (t) and most likely represents a Tornwaldt cyst. High signal intensity is due to elevated protein content within the cyst.

Tracheolaryngomalacia

Tracheolaryngomalacia is another neonatal entity that can cause airway narrowing and that is usually outgrown with time. The children have inspiratory stridor because the floppy laryngeal cartilages collapse under the effects of negative inspiratory pressure. The collapse of the airway with inspiration can be demonstrated at fluoroscopy.

Venous Vascular Malformations

Venous vascular malformations, with or without evidence of phleboliths, frequent the tongue. Previously, these were called hemangiomas, but this term is now relegated to those neoplastic lesions that tend to spontaneously regress in childhood or in response to steroids (capillary hemangiomas). Forty percent of venous vascular malformations are in the head and neck, followed by the extremities and the trunk. Venous vascular malformations are often dense on noncontrast CT and enhance avidly. They are most commonly seen in the skin and subcutaneous tissue, but populate the entire aerodigestive tract and nonmucosal spaces. These mucosal lesions grow with age and are evident because of their coloration on endoscopy.

Abscesses

Abscesses have low-density centers and a peripheral rim of enhancement on CT. Adjacent inflammation of the fat is due to neighboring cellulitis and fasciitis. On MR, inflammatory lesions are very bright on T2WI because of the marked amount of edema and swelling associated with abscesses. A peritonsillar location is the most common site of abscess in children, followed by the retropharyngeal region. Occasionally, one identifies a true abscess in the nasopharynx mucosa, although this is uncommon. Retropharyngeal extension of such an infection is a complication to be excluded on imaging studies. Pharyngitis and retropharyngitis can lead to Grisel syndrome (torticollis with rotatory subluxation of C1 on C2 secondary to an adjacent inflammatory mass). More often, what one is calling a retropharyngeal abscess is really necrotizing retropharyngeal lymphadenitis due to pharyngitis or tonsillitis, and need not be drained surgically. If the collection crosses the midline, call it an abscess. If it is paramedian along the expected location of retropharyngeal nodes, call it necrotizing adenitis.

Adenitis

Children seem to have a predilection for dramatic adenitis. Posterior triangle reactive adenopathy often accompanies the ubiquitous middle ear infections of young childhood. Pharyngitis can lead to complications of retropharyngitis, now recognized as an inflammatory process usually mediated by retropharyngeal adenitis, not direct spread (Fig. 14-14). Nonetheless, it can be a fulminant infection that can require surgical intervention.

Figure 14-14 Retropharyngeal adenitis. A, A retropharyngeal low-density collection likely represents necrotizing adenitis from the antecedent pharyngitis. Note the low density in the retropharyngeal space away from the node that may be due to either edema or phlegmon. B, Spread inferiorly from the nasopharyngeal level can occur due to the potential space afforded by the retropharyngeal fat and “danger space.” (Ah! but that is better left for a discussion in Chapter 15!) C, Spreading all the way down to the tracheal level—and beyond—is possible.

Castleman Disease

Castleman disease (angiofollicular hyperplasia) is a nodal disease that can be seen in the chest (70% of cases) and the head and neck (10%). Usually the patient is asymptomatic and younger than age 30 years. The unique feature of these nodes is their avid enhancement because of hypervascular stroma (Fig. 14-15). The nodes are nonnecrotic. There may be a stellate area of nonenhancement in the center of the enhancing nodes.

Figure 14-15 Castleman disease. The nodal mass on this enhanced computed tomography scan is of the same density as the thyroid gland. Such enhancing node (c) is suggestive of angiofollicular hyperplasia (Castleman disease), thyroid carcinoma, Kaposi sarcoma, some lymphomas, and Kimura disease.

Mononucleosis

Mononucleosis, caused by Epstein-Barr virus (EBV) infection, is another inflammatory source of multiple enlarged nonnecrotic lymph nodes. The differential diagnosis includes acquired immune deficiency syndrome (AIDS) and sarcoidosis. In AIDS and mononucleosis the lymphoid tissue of Waldeyer’s ring (adenoids, palatine tonsils, and lingual tonsils) may be hypertrophied, and bilateral nodes are the rule (Fig. 14-16). If intraparotid lymphoepithelial cysts are present, HIV infection is more likely. If the parotid glands are enlarged and infiltrated diffusely, sarcoidosis may be suggested, but a chest radiograph with bihilar adenopathy may be the best clue. Otherwise the differential diagnosis may rely on serology or the appropriate history.

Figure 14-16 Large lymph nodes with Waldeyer’s ring lymphoid hyperplasia. Note the enlarged lymph nodes (n) in the neck and the enlargement of Waldeyer’s ring tissue in the palatine tonsils (w). Differential diagnosis includes AIDS, mononucleosis, lymphoma, sarcoidosis, and pharyngeal carcinoma with malignant lymphadenopathy.

Cat Scratch Fever

Another “zebra” that can cause bilateral lymph nodes, including intraparotid nodes, is cat scratch fever. There often is edema surrounding the nodes. The etiologic agent in this infection has recently been characterized as a gram-negative intracellular bacterium (Bartonella henselae). If you quiz the clinician about a cat scratch history and actually come up with the diagnosis, you’ll be a star in his or her eyes forever. It is a self-limited disease after a cat scratch or flea bite that may manifest regional lymphadenopathy, fever, and malaise, but can progress to encephalopathy and neuropathy. Parinaud oculoglandular syndrome, characterized by unilateral conjunctivitis with polypoid granuloma of the palpebral conjunctiva, and preauricular, parotid, and periparotid lymphadenopathy can be caused by Bartonella infections. The diagnosis is confirmed by positive serologic tests or positive polymerase chain reaction assays to the bacterium.

Sinus Histiocytosis

Sinus histiocytosis may cause massive nodes. These may develop egg-shell calcification after interferon therapy.

Kikuchi Disease

Kikuchi disease, histiocytic necrotizing lymphadenitis, predominantly affects young adults of Asian ethnicity. The etiology is unclear, but is probably viral, and the patients present with adenopathy, fever, and leukopenia. It is associated with large necrotic and nonnecrotic, enhancing and nonenhancing adenopathy. The CT appearance of Kikuchi disease can simulate lymphoma and other nodal diseases that have necrosis, such as metastasis and tuberculosis.

Kimura Disease

Kimura disease, another import from the Far East, is a chronic inflammatory process with associated diffuse hypervascular adenopathy in the cervical chains favoring the submental and submandibular regions, eosinophilia, and a predilection for Asian men age 10 to 30 years. The salivary glands may be swollen and tender. The nodes are round, solid, hypoechoic, and homogeneous. They have hilar hypervascularity on power Doppler scans (the sonographic features are what is best known about the disease).

Enlargement of lymphoid tissue as a response to inflammation in adjacent regions may affect all parts of Waldeyer’s ring. When this is seen, check for pharyngitis or tonsi llitis in children, mononucleosis in hormonally active teenagers, and HIV infection in adults.

Tuberculous Adenitis

The classic cause of an inflammatory cervical adenitis is tuberculous adenitis (scrofula), usually seen in Southeast Asians. The patients have painless posterior neck masses with or without systemic symptoms. The source of the infection is usually contaminated milk associated with Mycobacterium bovis, causing a subclinical pharyngitis. In the United States Mycobacterium tuberculosis is the most common cause. Atypical mycobacteria (Mycobacterium scrofulaceum especially) may also cause tuberculous adenitis. Concomitant pulmonary tuberculosis is relatively uncommon. The disease manifests as bilateral low-density necrotic lymph nodes, often in the level V posterior triangle distribution (Fig. 14-17). The nodes often have ringlike thick enhancement and appear multiloculated. Adjacent fat planes are obscured or edematous. The nodes often calcify after treatment (Box 14-2). The differential diagnosis of calcified nodes should include tuberculosis, other granulomatous diseases (fungi, sarcoidosis, and Thorotrast granulomas), treated lymphoma, anthrosilicosis, and metastatic thyroid carcinoma, adenocarcinoma, or squamous carcinoma.

Figure 14-17 Gallery of tuberculous adenitis. A, Scrofula. Axial enhanced computed tomography (CT) demonstrates calcified lymph nodes (arrows) in the posterior triangle (level V) of the neck in this patient with a history of tuberculous adenitis. Note that the lymph nodes are well differentiated from jugular (j) and carotid (c) vessels seen anteriorly and medially. B, The necrotic nodes in the right neck with soft tissue stranding and irregular margination begs the diagnosis of tuberculous adenitis, especially in a young person. C, Enhanced CT shows rim-enhancing nodes in the left neck infiltrated with “red snappers.”

Croup

Epiglottitis must be distinguished from croup, a viral infection that occurs in children younger than those affected by epiglottitis. Parainfluenza 1 or 2 and influenza A are the most common pathogens. Croup is characterized by edema of the glottis and subglottis such that the normal contours of the laryngeal ventricle and true cords are obliterated, and a smooth steeple-shaped laryngeal airway is produced. Croup is a much less morbid disease than epiglottitis and should be distinguishable on the basis of plain films (Table 14-1). Woof, woof—sounds like the classic barking cough of croup.

Table 14-1 Differentiation of Croup from Epiglottitis

Granulomatous inflammatory conditions, including tuberculosis, sarcoidosis, giant cell reparative granulomas, Wegener granulomatosis, Langerhans cell histiocytosis, and candidiasis may affect the larynx. Of these, tuberculosis has a propensity for invading the cartilage. Relapsing polychondritis can affect the cricoarytenoid joints.

Cysts

Mucus retention cysts that occur in the aerodigestive system as a sequela of previous infections or obstruction of minor salivary glands can be seen anywhere in the head and neck mucosa. In the nasopharynx, they are often seen laterally around the fossa of Rosenmüller. These cysts usually have low signal intensity on T1WI and high signal intensity on T2WI. Midline mucus retention cysts and Tornwaldt cysts with similar signal intensities are indistinguishable. Occasionally one will also see cysts deep to the mucosa that are along the pathway of the eustachian tube heading to the middle ear cavity. Rarely, these lesions may grow large enough to cause airway compromise. Anterior to the epiglottis, one may find the low-density, nonenhancing vallecular cyst. It may simulate a thyroglossal duct cyst but is usually off-midline.

Fistula

If a fistula in the tonsil is identified, consider a branchial cleft anomaly as a possible cause. Typically, the second branchial cleft fistulae drain to the tonsil and may or may not be associated with a cystic lesion in the soft tissues of the neck near the angle of the mandible. Actinomycosis is an unusual cause of peritonsillar fistulae.

Laryngotracheal Papillomatosis

Laryngotracheal papillomatosis refers to a viral infection that is seen most commonly in children and is probably due to transmission of the human papillomavirus types 6 and 11 at the time of passage through the birth canal. The true cords are the most common laryngeal site. This disease is currently treated with laser surgery and steroids, but the papillomas commonly recur. When the branches of the trachea and bronchi are affected, postobstructive pneumonias and respiratory compromise may occur.

Macroglossia

Inflammation/edema of the tongue may occur with acute allergic reactions and is one of the complications of iodinated contrast injections of which all radiologists should be aware. Treatment is dependent on severity and airway compromise but have the EpiPen, Benadryl, and steroids ready. Diffuse macroglossia may be present in patients with hypothyroidism, amyloidosis, Down syndrome, glycogen storage diseases, mucopolysaccaridoses, and neurofibromatosis, among other conditions (Box 14-3 and Fig. 14-18).

Figure 14-18 Diffuse amyloidosis. This patient had amyloidosis that affected the nasopharynx (A), tonsils (B), larynx, trachea (C), and the lymph nodes (seen in B, arrows) of the neck, which led to macroglossia and more.

Odontogenic Lesions

Numerous odontogenic abnormalities may be found within the oral cavity, the most common of which is the lytic lesion known as the radicular (periapical) cyst (Table 14-2). This is a lucent lesion of either the mandible or the maxilla and is associated with an infected tooth. These lesions rarely come to the medical radiologist; usually the dentist diagnoses them on bite-wing films. The second most common odontogenic cystic lesion is the dentigerous cyst. This cyst is associated with an unerupted tooth and is usually seen in the mandible, particularly around the molar region. Both the radicular cyst and the dentigerous cyst are usually unilocular, as opposed to the keratocyst and the ameloblastoma, which are benign but aggressive multilocular cystic lesions most commonly affecting the mandible (Fig. 14-19). Keratocysts are associated with the basal cell nevus (Gorlin) syndrome, in which patients have proliferative falcine calcification, multiple basal cell carcinomas of the skin, scoliosis, ribbon-shaped ribs, central nervous system tumors, and keratocysts of the mandible.

Table 14-2 Benign Lytic Dental Lesions

Figure 14-19 Dentigerous cyst. Coronal bone-targeted computed tomography demonstrates a large unilocular cystic mass (c) in the mandible with an associated unerupted tooth (t). This is virtually pathognomonic for a dentigerous cyst.

Sclerotic dental lesions also span the spectrum of inflammatory, benign neoplastic, and malignant lesions (Table 14-3). Dental disease is daunting due to dumbfounding and duplicative distributions and depictions of different dense and destructive diagnoses.

Table 14-3 Sclerotic Dental Lesions

Pharyngitis and Laryngitis

Benign inflammatory disease occurs frequently in the oropharynx, mostly manifesting as tonsillitis and pharyngitis. Because this is an easily made clinical diagnosis in the proper setting, no imaging of these conditions is typically required. Nonetheless, occasionally one may find a peritonsillar abscess in a patient who does not respond to antibiotics for tonsillitis. The typical microorganisms that cause a tonsillar abscess include Streptococcus pneumoniae, Streptococcus viridans, and occasionally gram-negative anaerobes. Often one is dealing with multiple bugs at once. Calcifications in the adenoids are not uncommon after infections resolve. These are of no import and do not implicate granulomatous infections.

Almost all of us have experienced the inconvenience (and serendipitous benefits) of laryngitis. This condition is usually associated with a viral upper respiratory tract infection and is benign and self-limited. Chronic laryngitis may actually be due to laryngeal nodules, a nonneoplastic reaction to chronic voice abuse.

Supraglottitis

We use the term supraglottitis because most cases of “epiglottitis” will affect the aryepiglottic folds and even the superior aspects of the arytenoids. In some cases the soft palate and prevertebral swelling may be the predominant factor in creating upper respiratory symptoms. Epiglottitis is a life-threatening illness that generally is seen in 2- to 4-year-old children. This is a bacterial infection of the epiglottis that is usually caused by Haemophilus influenzae. The epiglottis is markedly thickened (thumb-shaped), and dilation of the airway above the epiglottis is present. Manipulation of the epiglottis in the acute setting may cause diffuse laryngeal edema, producing acute respiratory compromise. Fifty percent of infants with this disorder ultimately require intubation. Epiglottitis is generally a clinical diagnosis with imaging limited to a confirmatory upright lateral plain film (Fig. 14-20). The patients often have increased stridor when they are placed supine; therefore cross-sectional imaging is not recommended—unless you have a gutsy radiologist. Furthermore, you want to keep the patient in a location close to where an emergency tracheostomy can be performed, which is usually not in an outpatient imaging center.

Figure 14-20 Epiglottitis. The epiglottis (arrows) and aryepiglottic folds (open arrows) are markedly thickened in this patient with epiglottitis. The case is unusual in that it occurred in an adult (note the degenerative change in the cervical spine). Make this diagnosis on an upright lateral plain film, one of the last indications for plain radiography in neuroradiology.

Streptococcus may predominate as an organism in adult supraglottitis. The infection is milder in adults and is less likely to cause acute respiratory arrest or obstruction. Adult supraglottitis is a more indolent infection than pediatric epiglottitis because adults can tolerate more supraglottic and prevertebral swelling than children. In adults, the ratio of the width of the epiglottis to the anteroposterior width of C4 should not exceed 0.33 (sensitivity, 96%; specificity, 100%), the prevertebral soft tissue to C4 ratio should not exceed 0.5 (sensitivity, 37%; specificity, 100%),and the hypopharyngeal airway to the width of C4 ratio should be less than 1.5 (sensitivity, 44%; specificity, 87%); if not, epiglottitis should be suspected. Look for aryepiglottic folds enlargement and arytenoid swelling.

Pharyngoceles and Laryngoceles

Pharyngoceles may occur in patients with chronic increased intrapharyngeal pressure such as in horn blowers (Dizzy Gillespie). These lesions are usually air-filled but occasionally may become obstructed and fill with fluid. The laryngocele is an outpouching of the laryngeal ventricle caused by obstruction of the ventricular saccule. The saccule is a superolateral extension of the ventricle into the paraglottic space. A laryngocele may be filled with either air or fluid (so-called saccular cyst) and is seen frequently in people playing wind instruments, who have chronic increased intraglottic pressure. The laryngocele is characterized as being internal, mixed, or external in its location. The internal laryngocele remains confined by the thyrohyoid membrane, whereas the external laryngocele protrudes through the thyrohyoid membrane. By definition the lesion arises within the laryngeal ventricle so that an isolated external laryngocele is almost unheard of; most lesions are in fact mixed laryngoceles, which have components both internal and external to the membrane. Occasionally the laryngocele becomes infected and it is then termed a pyolaryngocele.

Occasionally, a laryngocele may arise because of neoplastic processes (Fig. 14-21). To exclude a carcinoma at the saccule, endoscopy to evaluate the ventricle is recommended in patients with laryngoceles. Imaging studies should allow careful scrutiny of lesions in this region, which may be blind to endoscopy because of the overhanging shelf of the false cord.

Figure 14-21 Laryngocele associated with laryngeal carcinoma. A, This patient had a transglottic squamous cell carcinoma (c) that obstructed the saccule of the laryngeal ventricle on the right side. Internal laryngocele (l) developed in the paraglottic soft tissue. B, T2-weighted image (T2WI) demonstrates the fluid-filled laryngocele (l), also known as a saccular cyst, in the paraglottic tissues. This should not be confused with squamous cell carcinoma, which would not be as bright on T2WI.

Post-transplant Lymphoproliferative Disorder

Post-transplant lymphoproliferative disorder (PTLD) is one of these crossover diseases between a reactive node, a benign neoplasm, and a malignant neoplasm. The aggressiveness of the entity ranges widely from benign lymphoid hypertrophy to myeloma, to monoclonal lymphomas, to polyclonal lymphomas, all from the EBV infection leading to B-cell proliferation. Basically, you can find enlarged nodes in the abdomen, chest, and neck (in descending order of frequency) in patients after whole organ transplants (heart, liver, kidney, or bone marrow). The inciting event appears to be an infection by EBV, leading to a proliferation of B cells. If the T cells are deficient, as in transplant patients or HIV infections, this B-cell mass production gets revved up. Although this may result in a polyclonal lymphoproliferation, if unabated, a monoclonal dominant spike may appear. In some of these patients, lymphoma develops; in others the adenopathy resolves with manipulation of medications to produce a reduction in the degree of immunosuppression. Chemotherapy may be required in some.

Post-transplant lymphoproliferative disorder can also affect the adenoids and tonsils and is usually seen after solid organ transplantations (lung is most common). The onset of this process may range from months to years after the transplant. Surprisingly, PTLD can present as a necrotic mass in the nasopharynx.

Ranula

A final inflammatory lesion of the oral cavity is the ranula (mucus escape cyst). This is a cystic lesion that is due to obstruction of the sublingual gland duct or minor salivary gland of the floor of the mouth, which causes a backup of secretions. The obstruction may be due to previous infection, trauma, or calculi. Depending on whether the ranula protrudes through the mylohyoid musculature, the lesion may be termed simple (above the mylohyoid) or plunging (through the muscle). Do not pooh-pooh this minutia because it makes a difference to the surgeon—the simple ranula is approached via an intraoral resection, whereas the plunging ranula requires a submandibular or transcervical or combined intraoral and cervical resection. The ranula’s wall usually enhances. The ranula may have a pointed edge along its anterior extent in the sublingual space at the site of obstruction (Fig. 14-22). Rupture of a ranula can cause an encapsulated mucus-containing infection in the deep tissue of the neck.

Figure 14-22 Simple ranula. A, Note the cute little lesion in the sublingual space on the left. B, It has fluid intensity on T2-weighted image. C, Only peripheral enhancement is seen. This is a quintessential simple ranula, probably from a sublingual duct obstruction.

SAPHO

SAPHO (synovitis, acne, palmoplantar pustulosis, hyperostosis, and osteitis) syndrome is associated with diffuse sclerosing osteomyelitis of the mandible. The inflammation can spread from the temporomandibular joint to the skull base to the cochlea, leading to deafness.

Zenker’s Diverticulum

Zenker’s diverticula occur near the cricopharyngeus muscle and protrude posteriorly. They are best demonstrated by gastrointestinal radiologists and barium. They increase in frequency and size with age and develop at Killian’s dehiscence, an area of weakness between the cricopharyngeus and the inferior pharyngeal constrictor muscles. The patient may complain of dysphagia, bad breath, aspiration pneumonia, or regurgitation of undigested food. A Killian-Jamieson lateral pharyngoesophageal diverticulum protrudes laterally and is typically smaller than a Zenker’s diverticulum.