Salivary Gland Disease in Children




Key Points





  • Most salivary gland lesions in children have an inflammatory origin.



  • Accurate diagnosis of salivary gland disorders depends on a thorough history and a good physical examination.



  • The differential diagnosis of salivary gland masses includes acute or chronic inflammatory and/or infectious conditions, congenital lesions, vascular malformations, benign or malignant tumors, traumatic injury, and many systemic diseases.



  • Common bacterial etiologies of sialadenitis include Staphylococcus aureus and anaerobes. Viral etiologies include paramyxovirus (mumps), Epstein-Barr virus, cytomegalovirus, parainfluenza virus, adenovirus, coxsackievirus, and human immunodeficiency virus.



  • Hemangiomas are the most frequently encountered benign tumors in the parotid area, and pleomorphic adenomas are the most common benign intrinsic parotid tumors.



  • Salivary gland neoplasms are more likely to be malignant in children than in adults. Mucoepidermoid carcinoma is the most common salivary gland malignancy in children (>50%), and adenoid cystic and acinic cell carcinomas comprise most of the remainder.



  • A solid, firm, and fixed salivary mass that persists for more than 4 to 6 weeks is usually an indication for open surgical biopsy and/or excision.



  • Ultrasound with or without fine-needle aspiration can be very useful in the diagnosis of most parotid and submandibular gland diseases in children. Cross-sectional imaging with computed tomography or magnetic resonance imaging with contrast is helpful for a thorough evaluation of the nature and extent of salivary gland masses.



  • Sialoendoscopy is a minimally invasive and effective tool for the diagnosis of salivary gland ductal pathology (inflammation, stenosis, stricture) and for the treatment of sialolithiasis and juvenile recurrent parotitis.



  • Sialorrhea is seen mainly in patients with neurologic disorders and is mostly caused by an inability to control oral secretions rather than an overproduction of saliva. Sialorrhea may lead to medical complications such as skin infections, choking, aspiration, pneumonia, feeding issues, and speech problems; excessive drooling may also cause social or psychological problems or interfere with the patient’s daily care and rehabilitation therapies, creating an additional burden on their caregivers.



  • Treatment options for sialorrhea include rehabilitation (positioning, oral motor, behavior therapy), medical treatment (anticholinergics, botulinum toxin injection), and/or surgery (submandibular gland excision, duct ligation or relocation).



Salivary gland disorders in the pediatric population remain an uncommon entity but are not infrequently seen in a pediatric otolaryngology practice. The differential diagnosis includes acute or chronic inflammatory and/or infectious conditions, congenital lesions, vascular malformations, benign or malignant tumors, traumatic injury, and many systemic diseases ( Box 22-1 ).



Box 22-1

Etiologies of Pediatric Salivary Gland Disorders


Inflammatory


Acute





  • Bacterial: lymphadenitis or suppurative adenitis ( Staphylococcus aureus, Streptococcus viridans , anaerobes)



  • Viral




    • Mumps



    • EBV



    • HIV



    • Coxsackievirus A



    • Echovirus



    • CMV



    • Parainfluenza



    • Adenovirus




Chronic





  • Obstructive




    • Mucocele/ranula



    • Sialolithiasis



    • Sialectasis




  • Granulomatous




    • Atypical mycobacteria



    • Cat-scratch disease



    • Actinomycosis



    • Sarcoidosis



    • Toxoplasmosis



    • Histoplasmosis




Congenital





  • Agenesis



  • Branchial cleft cyst or fistula



  • Dermoid



  • Ductal cyst



  • Ranula



Neoplastic


Benign





  • Pleomorphic adenoma



  • Warthin tumor



  • Lipoma



  • Monomorphic adenoma



  • Neurofibroma



Malignant





  • Primary




    • Mucoepidermoid carcinoma



    • Acinic cell carcinoma



    • Adenocarcinoma



    • Adenoid cystic carcinoma



    • Lymphoma



    • Rhabdomyosarcoma




  • Metastatic



Vascular Malformations





  • Hemangioma



  • Lymphatic malformation



  • Venous anomaly



  • Arteriovenous malformation



Autoimmune





  • Sjögren syndrome



  • Benign lymphoepithelial disease



  • Wegener granulomatosis



  • Sarcoidosis



Traumatic





  • Blunt



  • Penetrating



  • Radiation induced



CMV, cytomegalovirus; EBV, Epstein-Barr virus; HIV, human immunodeficiency virus.



A good history and physical examination are extremely useful in diagnosing the specific salivary gland disorder. An algorithm for evaluation of pathology in the parotid gland, the most common salivary gland affected in children, is illustrated in Figures 22-1 and 22-2 . Ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and fine-needle aspiration biopsy (FNAB) have proven valuable for a more thorough evaluation of the nature and extent of salivary gland masses. Sialoendoscopy has become a valuable tool in the diagnosis of ductal pathology such as inflammation, stenosis, and stricture and is also valuable in the management of sialolithiasis and juvenile recurrent parotitis. A comprehensive understanding of the anatomy, physiology, and function remains essential for the diagnosis and treatment of salivary gland disorders.




FIGURE 22-1


Differential diagnosis and approach to congenital and acute acquired parotid enlargement. EBV, Epstein-Barr virus; HIV, human immunodeficiency virus.



FIGURE 22-2


Differential diagnosis and approach to chronic acquired parotid enlargement. FNA, Fine-needle aspiration; FU, follow-up.




Anatomy and Physiology


The three pairs of major salivary glands are the parotid, submandibular, and sublingual glands ( Fig. 22-3 ); these are in addition to hundreds of minor salivary glands, which are predominantly located in the palatine mucosa. All salivary glands are derivatives of ectoderm. During development, ectodermal rests pierce surrounding mesenchyme and arborize before terminating into multiple acini. Each salivary gland is an aggregate of multiple salivary secretory units composed of acini and ducts ( Fig. 22-4 ). Saliva produced by the secretory cells of the acini passes through intercalated, intralobular, and excretory ducts before collecting in the main excretory duct of the gland. The parotid gland consists of predominately serous acini that secrete a watery serous fluid. The submandibular gland is composed of a mixture of serous and mucinous acini, whereas the sublingual gland and minor salivary glands contain predominantly mucinous acini that secrete thick mucinous fluid. The primary saliva secreted is modified as it transits through the ductal system.




FIGURE 22-3


Anatomy of the major salivary glands.



FIGURE 22-4


An acinus histologic section.


The parotid is the largest major salivary gland and is the first to develop in utero. Rarely, agenesis of the parotid and/or submandibular glands has been reported ( Fig. 22-5 ). The parotid becomes encapsulated after the development of the lymphatic system and is therefore the only salivary gland that contains lymph nodes. It lies between the external auditory canal, the ramus of the mandible, and the mastoid tip and is artificially divided by the facial nerve into a deep and a superficial lobe. It is separated by the stylomandibular ligament from the submandibular gland, and both glands are covered by the superficial portion of the deep cervical fascia. The parotid acinar units and ductal systems drain into a final secretory duct known as the Stensen duct. The latter arises from the anterior border of the parotid gland, courses superficial to the masseter muscle in a direction parallel and inferior to the zygoma, then turns sharply, pierces the buccinators, and enters the oral cavity opposite the second upper molar. Detached accessory parotid glands have been described, located at variable distances from the main gland along the Stensen duct in 21% of cadaver specimens. The Stensen duct is 4 to 7 cm in length and has a variable diameter along its length; histologic studies reveal a mean diameter that ranges between 0.5 mm and 1.4 mm, a narrowing at the middle of the duct, and the smallest diameter at the ostium (0. 5 mm).




FIGURE 22-5


Unilateral agenesis of the left parotid gland. The arrow points to the normal parotid gland on the contralateral side.


In infants and young children, the facial nerve is much more prone to injury during salivary gland surgery than in adults, because the anatomic landmarks are not as well defined. Prior to complete pneumatization of the mastoid air cells, the facial nerve takes a more abrupt and lateral course after exiting the stylomastoid foramen and can be found just deep to the subcutaneous tissue prior to entering the parotid gland. Because the parotid gland is not completely developed, a large portion of the nerve may be exposed. Finally, the marginal mandibular branch of the facial nerve is located more superiorly in children compared with adults, often taking a superficial course over the mandible. It is only after the development of the mastoid tip and tympanic ring that the facial nerve takes a deeper and more protected position behind the mastoid bone and tragal cartilage.


The submandibular and sublingual glands are small in young infants and are often anatomically contiguous. Rapid growth of these glands occurs during the first 2 years of life. The submandibular gland is located in the floor of the mouth and consists of a larger superficial part separated from a smaller deep part by the posterior free edge of the mylohyoid muscle. The superficial part rests between the anterior and posterior digastric tendons just below the body of the mandible and is bounded superomedially by the mylohyoid muscle and inferiorly by platysma and the investing layer of the deep cervical fascia. The deep part is located between the mylohyoid and the hyoglossus muscles. Acinar units and ductal systems drain into a single and final secretory duct known as the Wharton duct. The submandibular duct emerges from the medial deep part of the gland and runs anteriorly above the mylohyoid and on the lateral surface of the hyoglossus and genioglossus muscles. It is 5 cm long, has a mean diameter that ranges between 0.5 mm and 1.5 mm, and it opens in the floor of the mouth through a papilla lateral to the tongue frenulum. Its minimum width is located at the ostium (0.5 mm). The duct has an intricate relation with the lingual nerve (see Fig. 22-3 ). Posteriorly, the lingual nerve lies above the duct, then, as the nerve descends, it crosses the lateral side of the duct and passes below it, winding round its lower border before crossing it medially and ascending toward the genioglossus. The hypoglossal nerve is located anterior, deep and medial to the submandibular gland. It also courses deep to the Wharton duct and to the anterior belly of the digastric muscle.


The sublingual glands lack a capsule and are located in the floor of the mouth above the mylohyoid muscle in the space between the mandible and the genioglossus muscles, immediately below the oral mucosa. They drain directly via several small ducts (ducts of Rivinus) into the floor of the mouth, and at times some of the ducts collect into a larger common duct, known as the Bartholin duct, which empties into the Wharton duct. The sublingual glands are often the source of ranulas, which are cystic, mucus-filled swellings in the floor of the mouth.


The remaining upper aerodigestive tract is lined by hundreds of minor salivary glands that lie just deep to the mucosa. The highest concentration of minor glands is in the buccal, lingual, labial, and palatal regions. Each minor gland has a draining duct that opens directly into the mucosa. Occlusion of these ducts can lead to small mucoceles that are frequently found along the lower lip of young children.


Salivary flow is controlled via the autonomic nervous system. The parotid gland receives parasympathetic secretomotor innervation from preganglionic fibers that arise in the inferior salivatory nucleus of the medulla. These fibers travel with the ninth cranial nerve to exit the skull via the jugular foramen. They then leave the glossopharyngeal nerve as the Jacobson nerve and reenter the skull via the inferior tympanic canaliculus. The fibers pass through the middle ear space over the promontory of the cochlea (tympanic plexus) and exit the temporal bone as the lesser petrosal nerve. The lesser petrosal nerve exits the middle cranial fossa through the foramen ovale, where the preganglionic fibers synapse in the otic ganglion. The postganglionic fibers travel with the auriculotemporal nerve to supply the parotid gland. The submandibular, sublingual, and minor salivary glands receive parasympathetic secretomotor innervation from preganglionic fibers, which originate in the superior salivatory nucleus in the pons. These fibers leave the brainstem as the nervus intermedius to join with the facial nerve. They then leave the facial nerve with the chorda tympani in the mastoid segment and travel through the middle ear and petrotympanic fissure to the infratemporal fossa. The presynaptic fibers are then carried by the lingual nerve, a branch of the mandibular division of the trigeminal nerve, to synapse in the submandibular ganglion. Postganglionic fibers innervate the submandibular and sublingual glands. Postganglionic sympathetic innervation of the major salivary glands is through the external carotid plexus, originating from the superior cervical ganglion.


Frey syndrome, also known as gustatory flushing or auriculotemporal nerve syndrome, is characterized by facial skin flushing and sweating that classically occurs in response to gustatory or olfactory stimuli. Its postulated etiology is related to the aberrant regeneration of the parasympathetic fibers that normally innervate the parotid gland. The traumatized regenerated fibers innervate instead of the vessels and sweat glands of the overlying skin, which are normally supplied by sympathetic nerve fibers. This occurs as both sympathetic and parasympathetic fibers use acetylcholine neurotransmitters. In children, Frey syndrome can occur following any local trauma to the parotid area—such as after vaginal delivery with forceps or after postcondylar fracture or seizure —or after parotid surgery or infection (herpes zoster). The latent time required for the development of this condition can vary from days to several years following the insult. Frey syndrome has also been described to occur in a familial pattern in the absence of a history of perinatal trauma. Most children do not require any treatment. In adolescents with severe symptoms, intradermal botulinum toxin A injections are safe, effective, and well tolerated.


Saliva maintains moisture within the oral cavity, lubricates food, inhibits bacterial growth (lysozyme and immunoglobulin [Ig]), and begins the food digestion process (amylase). The amount of saliva secreted ranges between 0.5 and 1.5 L of saliva daily, depending on the size of the child. Saliva is a complex solution composed of mostly water (99%), electrolytes, proteins, and enzymes. High bicarbonate ion content is responsible for its relative alkaline pH of 7.4. Secretions from the parotid gland are mostly serous in nature with high water content and relatively lower mucin content. In contrast, the submandibular and sublingual gland secretions are mixed (mucous and serous), which renders a more viscous, mucin-rich saliva. Resting salivary secretions are produced predominantly by the submandibular glands (60% to 70% of total saliva). The parotid is the major contributor to stimulated saliva, and salivary flow increases with the sight and smell of food, with chewing and taste sensations, and with esophageal and gastric reflex–mediated responses. Parasympathetic postganglionic cholinergic nerve fibers lead to the secretion of large amounts of a low-protein, serous saliva. On the other hand, sympathetic stimulation of the salivary glands causes the secretion of a small and variable amount of thicker saliva, likely caused by contraction of the myoepithelial cells.




History and Physical Examination


A detailed history including the onset, duration, severity, and frequency of symptoms is crucial in the assessment of children with salivary gland disorders. Perinatal salivary gland swelling is more likely to be a congenital lesion, such as hemangioma or a lymphatic or vascular malformation. A gradual painless increase in size suggests a neoplasm, especially in older children. An acute onset of pain and swelling, especially with fever, indicates an inflammatory or infectious process. Ductal obstruction often presents with intermittent and recurrent postprandial swelling of the gland. Painless violaceous lesions of the skin are often seen with atypical mycobacterial infections that typically affect the preauricular and submandibular areas. A history of cat exposure raises the possibility of cat-scratch disease, and a history of sick contacts and vaccination should be elicited to rule out mumps; the patient should also be questioned on the presence of other systemic conditions, and involvement of more than one gland may indicate systemic involvement or autoimmune disease. A history of trauma suggests duct injury or disruption.


Physical examination should note the location, size, mobility, symmetry, tenderness, and consistency of the glands in addition to any overlying skin changes such as erythema, edema, dermal involvement, or presence of a fistula. A complete exam includes bimanual palpation performed with one hand externally and a gloved finger intraorally. The buccal mucosa, oral cavity, and floor of mouth should be inspected, and the ducts should be palpated for the presence of stones. Signs of trauma related to oral appliances or cheek biting may explain the source of ductal obstruction. Massaging the gland while observing the saliva expressed from the ductal opening can be useful to rule out ductal blockage or to identify pus, therefore confirming the presence of an obstruction or an infection, respectively. Punctal edema with clear saliva is suggestive of viral sialadenitis.


Facial nerve function in all divisions, tongue mobility for hypoglossal nerve function, and general somatic sensation (fifth cranial nerve) should be documented. A salivary gland mass accompanied by facial nerve weakness is highly suspicious for a malignant process. In contrast to adults, solid lesions are more likely to be malignant in children, and the larger the gland of origin in children, the more likely a tumor will be malignant. A good history and physical exam will guide the need for additional investigations such as laboratory studies and diagnostic imaging.




Evaluation


Laboratory Studies


Laboratory studies may be helpful in narrowing down the differential diagnosis of salivary gland disease. The white blood cell count may confirm an infectious etiology if elevated and can also serve for follow-up on the response to treatment. C-reactive protein is a nonspecific marker of inflammation that can also be followed in cases of infections. Mumps serology and amylase levels may be useful in certain cases. Also, when multiple glands are involved, such as with bilateral cystic swelling of the parotid glands, investigations for immunosuppression or human immunodeficiency virus (HIV) infection should be entertained. Cultures of secretions expressed from the ductal orifice may help in identifying the causative organisms. In cases suspicious for mycobacterial infections, a purified protein derivative skin test and chest radiograph should be done. Serology for sarcoidosis and Sjögren syndrome may be useful occasionally.


Diagnostic Imaging


Multiple imaging modalities may be helpful for establishing the diagnosis and management plan of salivary gland lesions. Plain radiographs may illustrate radiopaque stones in the salivary gland ducts. However, up to 20% of submandibular and 80% of parotid duct stones will be radiolucent, which leads to false-negative results on plain films. Phleboliths, atherosclerosis of the lingual artery, and calcified lymphadenopathy will also appear as calcification on plain films and complicates their interpretation.


Ultrasound remains the most helpful test in the pediatric population, because it is noninvasive, inexpensive, widely available, and avoids radiation exposure. The precision of ultrasound for diagnosis of superficial parotid and submandibular gland lesions is comparable to that of CT or MRI. Ultrasound can detect up to 90% of stones greater than 2 mm and can distinguish benign from malignant lesions in the majority of cases. Ultrasound can also differentiate whether masses are within the gland or extraglandular with a very high accuracy. Although the facial nerve is not identified by ultrasound, the visualization of the intraparotid vasculature helps distinguish the deep from the superficial lobe of the parotid. Ultrasound is useful to diagnose abscesses and vascular lesions, and can also assist in guiding fine-needle aspiration of superficial lesions. Despite all its advantages, ultrasound remains an operator-dependent test and is not an appropriate tool for a complete evaluation of the nature and extent of salivary gland masses; cross-sectional imaging with CT and/or MRI is often necessary. These modalities are necessary to evaluate deep parotid lesions, parapharyngeal extension, retropharyngeal and deep cervical lymphadenopathies, and skull base extension. CT is often the test of choice in inflammatory and obstructive conditions such as sialadenitis, ductal stones or stenosis, ranulas, and abscesses. It can provide great anatomic detail and can assist in surgical planning. Imaging is performed both before and after administration of intravenous (IV) contrast with both soft tissue and bone algorithms. CT can also be useful in solid masses to identify any erosion of the surrounding bone. Although noncontrast CT is useful in cases of salivary gland stones, IV contrast is needed when information about vascularity or abscess formation is desired. Despite the ionizing radiation, the CT scan has the advantage of being a short procedure, as opposed to MRI, and it can be done without the need for sedation in most cases. Currently, cone beam CT is being used more frequently, because it provides relatively high resolution of bony structures with a lower dose of radiation.


MRI is the test of choice in cases suspicious for an underlying neoplasm and in masses of the parapharyngeal space. It gives excellent soft tissue detail and the ability to identify tumor margin, extent, depth of infiltration, involvement of the facial nerve, and perineural spread. Standard axial T1- and T2-weighted images reveal tumor margins. Coronal, fat suppression, and gadolinium-enhanced images can help identify perineural spread. Flow voids assist in determining the nature of vascular malformations; high-flow lesions, such as arteriovenous malformations and hemangiomas, can be easily delineated from low-flow lesions such as lymphangiomas. Newer MR techniques can help delineate benign from malignant processes using dynamic contrast or diffusion-weighted methods. A principal advantage of MRI over CT scan in children is the absence of ionizing radiation; however, MRI remains a lengthy procedure that requires sedation or general anesthesia to obtain quality images. Also, MRI is more expensive and less readily available than other imaging modalities.


Traditional sialography consists of injecting contrast material into the Stensen or Wharton duct to detect duct stricture, stenosis, or sialoliths. As an invasive method that requires cannulation of the duct, sialography is less feasible in uncooperative children. Another disadvantage is that it also uses ionizing radiation. Sialography is being gradually replaced in many institutions by noninvasive imaging techniques. MR sialography allows for a precise morphologic evaluation of the salivary ducts up to second- and third-order branches without the need for duct cannulation. Also, it does not expose patients to ionizing radiation or contrast agents, and the examination may be carried out even in the setting of acute inflammation of the salivary gland. First described by Lomas in 1996 using the single-shot rapid acquisition with relaxation enhancement sequence, MR sialography has been validated by several studies using a number of different pulse sequences, including modified rapid acquisition with relaxation enhancement, fast spin-echo, constructive interference in steady state, and half-Fourier acquisition single-shot turbo spin echo.


Nuclear imaging studies may be useful in selected cases. Scintigraphy is a diagnostic test wherein radioisotopes are administered and taken up by the organ of interest, and the emitted radiation is captured by external gamma cameras to form two-dimensional images. Salivary gland scintigraphy with technetium-99 m (99mTc) pertechnetate can be used to assess the parenchymal and excretory function of all major salivary glands. After administering a single IV injection—which is very well tolerated—the uptake, concentration, and excretion of the tracer can be measured. A stimulated excretion fraction that measures the percent of trapped saliva emptied into the oral cavity in response to a sialogogue stimulus can also be calculated by the following formula: 1 − [(Net minimal postsialagogue counts)/(Net maximum presialagogue counts)] × 100. Net counts are those that remain in the salivary gland after subtraction of nonspecific background counts.


Scintigraphy can be useful to assess the residual function of the salivary glands after duct ligation or duct relocation surgery. It can also be helpful in the assessment of specific autoimmune and inflammatory diseases of the salivary glands such as Sjögren syndrome and those that result from radioactive iodine treatment and head and neck radiation therapy.


The radionuclide salivagram is a sensitive and specific imaging method for detecting tracheobronchial aspiration of oropharyngeal contents and secretions. The salivagram is particularly useful in patients who are unable to cooperate with or swallow adequately to allow a videofluoroscopy swallow assessment. Sodium pertechnetate is absorbed by the oral and gastric mucosa and therefore cannot be used for the salivagram. Rather, a small drop of saline (0.1 mL) that contains 99mTc-labeled sulfur colloid or 99mTc-diethylene triamine pentaacetic acid is placed sublingually or on the back of the tongue. Dynamic images are recorded, and chest images are obtained at the end of the study. Salivary aspiration is confirmed with the detection of positive radioactivity in the tracheobronchial tree. If aspiration is identified, continued imaging may reveal whether the aspirated tracer is spontaneously cleared from the airway. Patients who are able to clear their airway after aspiration have a better prognosis. In a recent study of children with severe cerebral palsy that compared three imaging modalities to document aspiration, the salivagram was the most frequently positive, followed by barium videofluoroscopy, whereas the milk scan was the least useful.


Sialoendoscopy


Sialoendoscopy was recently introduced as an alternative method for the diagnosis and treatment of obstructive and inflammatory salivary gland disorders. Advances in instrumentation have allowed the use of this method in the pediatric population to visualize the ductal anatomy as well as to remove stones that are beyond the reach of traditional transoral procedures. Endoscopy may also localize stones that have gone undetected by other imaging techniques. In the near future, this innovative method may become the gold standard for the investigation and treatment of many salivary gland pathologies. Indications for sialoendoscopy include chronic and acute inflammatory or obstructive conditions of the parotid and submandibular glands, juvenile recurrent parotitis, Sjögren syndrome, congenital and acquired ductal strictures, and sialolithiasis.


Several models of sialoendoscopes are available that differ based on size, degree of rigidity (flexible, semirigid, or rigid), and purpose. Diagnostic endoscopes are equipped with a fiberoptic light, image transmission, and occasionally an irrigation channel to evaluate pathology, but they do not allow intraductal instrumentation. Therapeutic endoscopes may be compact or modular. Compact sialoendoscopes come as a single unit that cannot be disassembled. A typical compact endoscope combines a fiber light transmission, a fiber image transmission, a working channel, and an irrigation channel within one compact instrument ( Fig. 22-6 ). An outer tube covers, stabilizes, and protects all of the components of this system.




FIGURE 22-6


Example of a modular sialoendoscope.


The Erlangen (Karl Storz) mini sialendoscopy zero-degree telescope comes in three sizes: 0.8, 1.1, and 1.6 mm. All three have an integrated lens and irrigation channel, however, only the 1.1 and 1.6 mm also include an instrumentation channel. The latter, also referred to as the working channel, allows the introduction of a microdrill and laser fiber to fragment larger stones, a balloon dilator for ductal stenosis, and a wire basket for stone fragment extraction ( Fig. 22-7 ). The 1.6-mm telescope is occasionally found to be too large for certain pediatric patients. An interesting feature of one compact semirigid endoscope series (Marchal model, Karl Storz) is a slight bend in the endoscope shaft near its distal tip. This can make steering easier in certain cases; however, it reduces the usable diameter of the working channel. In semirigid modular endoscopes, the optical fibers used for light and image transmission are combined into a single probelike component. This combined unit can be introduced into sheaths of various sizes; the gap between the optical system and the sheath’s outer wall is used as an irrigation channel, and combination of the optical system with a large single-lumen sheath or a double-lumen sheath permits the introduction of different instruments.




FIGURE 22-7


Stone-extractor wire basket contains a submandibular stone removed by sialoendoscopy.


A recent study found that sialendoscopy can be performed under local anesthesia in children older than 8 years who have satisfactory cooperative skills. The procedure starts with the identification of the salivary gland duct papillae, followed by serial dilation using salivary duct probes and dilators. Active infection is a contraindication for sialoendoscopy, because it may increase the risk of rupturing the duct. Also, visualization can be compromised by bleeding from the duct walls and by the presence of pus in the lumen. Whereas larger stone size was a contraindication in many studies, our experience is that a holmium laser can be used safely to fragment most stones. In some cases we use a combined approach, using the endoscope to localize the stone and an external or intraoral approach with a small incision to extract the stone at its location.


Biopsy


Fine needle aspiration (FNA) of the salivary glands was previously considered controversial because of the cytologic similarities between benign and malignant salivary gland tumors. However, a recent systematic review found FNA to have reliable sensitivity and specificity in diagnosing salivary gland pathology. FNA can be safely performed and can be done under local anesthesia in cooperative children. In cases where FNA is not diagnostic, open excisional biopsy is required, particularly in masses that persist longer than 4 to 6 weeks. For cases of suspected lymphoma, incisional biopsy is adequate. Examination of the draining lymph nodes should be performed both prior to and during excisional biopsies, and nodal resection should be performed if indicated.




Infectious Conditions


Bacterial Infections


Acute suppurative sialadenitis typically presents with a sudden onset of firm, erythematous swelling of the parotid area that extends to the angle of the mandible. It is associated with local tenderness and trismus and also with systemic signs of high fever and chills in severe cases. Sialadenitis can occur at any age and is more common in children younger than 2 months and in premature gavage-fed infants. It is usually unilateral and is more frequent in the parotid glands because of the thin serous character of the saliva produced by the parotid, which tends to be less bacteriostatic than the mucinous secretions of the submandibular and sublingual glands. Infection can be secondary to dehydration or salivary stasis. The latter can be caused by obstruction of the salivary gland duct by a sialolith, which is more common in the submandibular gland, or it can be secondary to ductal trauma, stricture, mass effect from surrounding tissue, autoimmune disorders, and congenital sialectasis. Ductal trauma can be caused by biting of the oral mucosa, dental appliances, and tooth eruption. Retrograde oral bacteria transmission via the salivary ducts is thought to be a contributing factor.


Massaging the gland may assist with expression of pus from the duct of the salivary gland involved, which is pathognomonic for bacterial sialadenitis. Culture of secretions is helpful to confirm the bacterial nature of the infection and to guide the treatment plan. The microbiology of acute suppurative parotitis is often polymicrobial. Staphylococcus aureus is the most frequently isolated pathogen, but anaerobes are also common. Other organisms besides S. aureus include Haemophilus influenzae , Peptostreptococcus , Streptococcus pneumoniae , Escherichia coli , and Bacteroides species.


Treatment includes adequate hydration, sialagogues (e.g., sour candy, lemon drops, and pickles), analgesics, and warm compresses to increase salivary flow and decrease inflammation. Systemic antibiotics are started empirically pending available culture results. IV antibiotics may be required for children with comorbidities or in cases of severe infections such as cellulitis or sepsis. The choice of antibiotic depends on the severity and the extent of the infection, the patient’s immune competence, and comorbidities, and it should be adjusted depending on the response to therapy and available culture results. Choices include amoxicillin/clavulanate (per os [PO]), ampicillin/sulbactam (IV), nafcillin (IV), clindamycin (PO or IV), cephalexin or cefazolin or cefuroxime with or without metronidazole (IV), and vancomycin or linezolid (IV; in cases of methicillin-resistant Staphylococcus aureus ) plus metronidazole (anaerobes). Close monitoring is important, because the infection has the potential to spread to the deep cervical fascia spaces. Recurrent salivary gland infections may lead to ductal scarring, which may be managed with sialoendoscopy and guided balloon dilation of the stenosis. A stent is placed occasionally. Surgical excision of the gland can be performed in cases of failure.


Signs of abscess development include palpation of a fluctuant mass in the involved salivary gland, which can be confirmed by ultrasound. At times, the fluctuant nature of the abscess may not be appreciated in the parotid gland because of the dense fascia that overlies the gland. Incision and drainage of a parotid abscess requires a parotidectomy incision, and care must be taken to avoid injury to the facial nerve. Parotid abscesses may be amenable to needle aspiration under local anesthesia to avoid a facial scar and the risks of a general anesthetic.


Treatment of a submandibular gland abscess requires an incision, which should be carried out two fingerbreadths below and parallel to the lower border of the mandible to avoid injury to the marginal mandibular branch of the facial nerve. A drain should be inserted to avoid recollection. Extension beyond the submandibular space can lead to Ludwig angina. Whereas the latter condition has most commonly an odontogenic etiology (i.e., second or third mandibular molar teeth), some cases originate from a submandibular gland infection or a suppurative parotitis. It is characteristically an aggressive, rapidly spreading brawny hard cellulitis that involves the submandibular space and the floor of the mouth bilaterally. This typically polymicrobial infection should be treated urgently with IV antibiotics and close airway monitoring. The currently preferred option for securing the airway is an elective, awake fiberoptic-guided nasotracheal intubation in the operating room, which obviates the need for tracheostomy in most cases. Tracheostomy is reserved for cases in which intubation is not feasible or is too risky.


Viral Infections


Viral sialadenitis is usually self-limited and responds to conservative management with warm compresses, sialagogues, analgesia, and hydration. It can be caused by a number of viruses that include mumps, Epstein-Barr virus, parainfluenza, adenovirus, cytomegalovirus, human herpesvirus 6 (HHV-6), HIV, coxsackievirus, and influenza.


Mumps


The incidence of mumps has significantly decreased since the introduction of the vaccine. Manifestations of mumps include bilateral parotid swelling, fever, chills, pain, trismus, and difficulty chewing. Mumps is more frequent in the winter and spring months, and 85% of cases occur in children. The incubation period is usually 14 to 21 days from exposure to onset of symptoms. Viral shedding in respiratory secretions precedes the onset of symptomatic illness by 2 to 3 days and lasts until the swelling remits. Parotid swelling is present in most patients; the contralateral parotid gland also becomes enlarged in 90% of cases, but this may be delayed by several days. The Stensen duct orifice may be erythematous and dilated. Complications are more commonly seen in older children and include orchitis, meningitis, encephalitis, sensorineural hearing loss, and pancreatitis.


The diagnosis of mumps is usually a clinical one. Serology testing, if performed, should be obtained as soon as the infection is suspected. Supporting evidence of mumps infection includes a positive IgM mumps antibody (stays positive up to 4 weeks), a significant rise in IgG titers between acute and convalescent specimens, or isolation of mumps virus or nucleic acid from infected fluid (saliva, urine, cerebrospinal fluid). A negative mumps IgM titer in vaccinated individuals does not rule out mumps. Leukopenia with relative lymphocytosis and elevated serum amylase may also be observed. Treatment is conservative and consists of adequate hydration, pain control, antipyretics, and respiratory isolation.


Epstein-Barr Virus


The Epstein-Barr virus (EBV), also known as human herpesvirus 4 (HHV-4) , is a causative agent in infectious mononucleosis and has been implicated as a major cause of acute inflammation of the salivary glands in pubescent children. Infection with EBV usually occurs by transfer of saliva that contains a high viral load from an actively replicating virus. The virus has a long incubation period that ranges from 30 to 50 days. Patients can be completely asymptomatic or may have a triad of fever, sore throat, and posterior cervical adenopathy. The adenopathy may involve the parotid or submandibular lymph nodes with subsequent involvement of adjacent glands. In severe cases, splenomegaly may occur, and the patient should be advised to rest and avoid exercise. Fatigue may persist for several months. Treatment is usually supportive, although corticosteroids may be required in severe cases.


EBV has been implicated in the development of salivary gland tumors and oral malignancies of nonodontogenic origin in addition to Burkitt lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma.


Human Immunodeficiency Virus


HIV-associated salivary gland disease is common in children. The clinical manifestations of pediatric HIV infection are varied and often nonspecific. These include lymphadenopathy, oral candidiasis, and failure to thrive. Over 50% of children with HIV present with head and neck masses, the majority of which involve the salivary glands. The parotid glands are the most frequently affected salivary glands and may be enlarged because of lymphoproliferative, cystic, or mixed hyperplasia in addition to intraglandular adenopathy. Bilateral cystic and painless enlargement of the parotid glands is pathognomonic for HIV infection. Slow, continuous enlargement of the glands is typical; cysts are often multiple, painless, and multiloculated. Many patients have reduced salivary flow, stasis of secretions, and xerostomia. Latent manifestation of viral infection with EBV and cytomegalovirus may also contribute to salivary gland pathology in patients with HIV infection.


A recent series of HIV-positive children who presented with salivary gland masses revealed that the majority of the masses were caused by reactive lymphadenopathy, benign lymphoepithelial cysts, or an underlying infection. However, almost 7% had an underlying neoplasm that included pleomorphic adenoma, lymphoma, and Kaposi sarcoma, among others.


Management of HIV-associated salivary gland disease is usually conservative. Aspiration may be indicated to alleviate large cysts that cause cosmetic deformity, but the fluid typically re-collects weeks to months later. Surgery is rarely required, although FNAB for cytologic analysis is helpful to establish the diagnosis in most cases. Open biopsy is indicated when a neoplasm is suspected, and CT or MRI can also be helpful in identifying occult pathology.


Granulomatous Conditions


Granulomatous diseases typically affect the salivary glands as a result of inflamed periglandular lymph nodes. Patients usually present with slowly progressive or atypical symptoms of infection and absence of ductal purulence. Etiologies include atypical mycobacterial infections, actinomycosis, tuberculosis, and sarcoidosis.


Atypical Mycobacteria


Atypical mycobacteria or nontuberculous mycobacteria (NTM) are a collection of acid-fast organisms that are ubiquitous in the environment. These infections appear to be increasing in number and severity in many developed countries worldwide. Infections are caused by ingestion, inhalation, or inoculation of the Mycobacterium bacilli from environmental sources that include water, soil, and food products. They can be classified into slowly growing and rapidly growing species. The slow-growing species include M. avium complex, M. marinum , and M. kansasii, and these typically require a few weeks to grow on culture. The rapidly growing species require a few days to grow on culture and include M. fortuitum , M. chelonae , and M. abscessus .


NTM infection of the salivary glands is most frequently seen in immune-competent children and typically presents in patients aged 1 to 5 years. The vast majority of NTM lymphadenitis in children is caused by M. avium complex, which includes M. avium , M. intracellulare , and M. haemophilum . Other etiologic organisms include M. kansasii and M. scrofulaceum . M. bovis infection has become less common since the widespread pasteurization of milk, and BCG vaccine was found to be protective against NTM in several studies.


Cervicofacial lymphadenopathy is the most common manifestation of NTM and usually involves the submandibular and parotid areas. As the disease progresses, the overlying skin becomes erythematous with a typical violaceous hue ( Fig. 22-8 ). Periparotid and submandibular lymph nodes are frequently involved with the formation of cutaneous fistulae or sinus tracts in advanced stages. The Mantoux test is often weakly positive. The chest radiograph is typically normal, although mediastinal nodes may be involved in certain cases. Diagnosis is based on clinical judgment and exclusion of other diseases. FNA may help to rule out an abscess; however, culture results can take 6 weeks until an organism is identified. Polymerase chain reaction (PCR) and PCR-restricted analysis are increasingly used to identify and differentiate atypical mycobacteria species. Imaging is not always required but may be useful at times. Ultrasonography reveals decreased echogenicity in the early stages, with intranodal liquefaction, matted nodes, and soft tissue edema in advanced stages. CT may reveal ring enhancement with central hypodensity and minimal to absent fat stranding.


Jul 15, 2019 | Posted by in OTOLARYNGOLOGY | Comments Off on Salivary Gland Disease in Children
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