Salivary Gland Disease in Children
Matthew K. Whitley
Karen B. Zur
Pediatric salivary diseases, both benign and malignant, are not as prevalent as those in the adult population. The nonneoplastic disorders include acute and chronic inflammation (bacterial and viral), cysts, granulomatous diseases, Sjögren syndrome, sialolithiasis, and sialorrhea. Neoplastic diseases are subcategorized into mesenchymal versus epithelial and further classified as benign or malignant. This potpourri of disorders can affect the major or minor salivary glands, but predominantly the parotids and submandibular glands.
The evaluation of salivary gland pathology is the same as that done for the adult population, with emphasis placed on a thorough history and physical examination. Each of the topics discussed in this chapter addresses specific diagnostic tools to assist in the evaluation as well as the currently recommended medical or surgical intervention or both.
INFLAMMATORY CONDITIONS
Acute and chronic inflammatory diseases of the major and minor salivary glands are the most common pediatric salivary disorders (Table 98.1).
Acute Sialadenitis
Acute Bacterial Sialadenitis
Acute sialadenitis, as its name implies, is an acute inflammation of the affected gland, characterized by tenderness, localized pain, and overlying edema. Occasionally, purulent drainage may be seen emanating from the duct of the involved gland. Salivary stasis, due to either decreased saliva production or duct obstruction, increases the risk of sialadenitis. Conditions such as sialolithiasis, duct strictures, trauma, congenital sialectasis, autoimmune conditions, and dehydration contribute to stasis. Because of the serous (and therefore less bacteriostatic) composition of the parotid gland, it is more susceptible to acute suppurative sialadenitis than is the mucinous submandibular gland. During the past decade, the use of antibiotics along with fluid hydration and electrolyte management has almost eliminated the development of fulminating acute suppurative parotitis in hospitalized surgical patients. The predominant organisms include aerobic and anaerobic bacteria. Common aerobes include Staphylococcus aureus and Haemophilus influenzae, whereas the predominant anaerobes are gram-negative bacilli and Peptostreptococcus species (1).
The treatment is the same as that in the adult population. Local measures to increase salivary flow such as glandular massage, use of sialogogues, local heat (i.e., warm compress), and hydration complement the use of systemic antibiotics. Initial choice of antimicrobials should include a penicillinase-resistant antistaphylococcal agent that can be adjusted if no clinical improvement is seen within several days or based on culture results.
Episodes of recurrent acute sialadenitis in children often resolve by puberty (2). A conservative approach between episodes includes intermittent dilation of the ducts to avoid stricture (see section on “Recurrent Juvenile Parotitis”). Sialography can be performed in these patients to rule out duct strictures or changes in gland architecture. If chronic changes are seen, sialadenectomy should be considered. When the submandibular gland is involved, excision of the gland is recommended. When the parotid is involved, the decision-making process is complicated by the facial nerve. Various surgical alternatives have been described with limited success (3). The most effective and reliable approach is a total parotidectomy with facial nerve preservation. A superficial parotidectomy alone increases the risk of recurrent infections because of possible sialocele formation.
Neonatal Sialadenitis
Infections of the parotid and submandibular glands are rare but increasingly recognized in the premature neonate.
The diagnosis is clinical and confirmed by a warm, tender, erythematous mass with expressible purulence from the gland’s duct.
The diagnosis is clinical and confirmed by a warm, tender, erythematous mass with expressible purulence from the gland’s duct.
TABLE 98.1 DIAGNOSIS AND MANAGEMENT: DISEASES OF THE SALIVARY GLAND | ||||||||||||||||||||||||||||||
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Acute suppurative sialadenitis of infancy is thought to be due to the reduction in salivary flow, immunologic immaturity, and presence of bacteria in the oral cavity of these neonates (4). Dehydration, prolonged orogastric tube feeding, and congenital anomalies of the floor of the mouth have also been associated with suppurative sialadenitis in the neonate (4). S. aureus and Pseudomonas aeruginosa are the most commonly identified pathogens. The management is similar to that of acute sialadenitis in the child and adult. Hydration and antimicrobial therapy should lead to a response within 48 to 72 hours. Unlike in the older population, it is important to avoid gland manipulation in a preterm child to reduce the risk of systemic septicemia (4). If no satisfactory improvement is seen, incision and drainage is recommended. Recurrences are uncommon.
The differential diagnosis of unilateral gland inflammation in this age group includes submandibular fat necrosis, infected lymphangioma, and cervical lymphadenitis. To confirm the diagnosis, ultrasonography can be performed but is not indicated.
Viral Sialadenitis
Mumps
Worldwide, the most common inflammatory condition affecting the parotid gland is mumps. Mumps is caused by the paramyxovirus, which has a 2- to 3-week incubation period and has been known to inflame the gonads, meninges, and pancreas as well. It is most commonly seen during the winter and spring. The contagious period occurs 2 to 3 days before the development of gland enlargement, with a prodrome characterized by malaise, fever, chills, anorexia, and a sore throat. The clinical findings are similar to those described for bacterial sialadenitis, except for the presence of purulence from the duct orifice. The management is symptomatic.
Salivary Gland Disease in the HIV Patient
Oral manifestations are one of the earliest clinical indicators of human immunodeficiency virus (HIV) infection and progression in children (5). It has been estimated that 4% of the HIV-infected children in the United States have salivary gland disease (6). Salivary gland disease in this population can be classified as enlargement, xerostomia, or both.
Salivary gland enlargement is most commonly seen in the parotid gland, followed by the sublingual and submandibular glands (7). It is characterized by a gradual growth causing facial asymmetry. Parotid enlargement has been associated with generalized lymphadenopathy and lymphoid interstitial pneumonitis, occurring between ages 4 months and 4.5 years (5). Theories abound regarding the etiology of the lymphoepithelial cysts seen in this condition. One of them posits a relation with T-lymphocyte CD8+ cell infiltration in the gland (5). Some have suggested that lymphoepithelial cysts are caused by the obstruction of the salivary ducts from lymph nodes that are entrapped during parotid gland development. These benign lymphoepithelial lesions are seen initially with progressive painless
swelling of the parotid (8). In the HIV population, they are bilateral in up to 80% of cases. Parotid pseudocysts are secondary to viral inflammation and are often the initial manifestation of HIV. Testing for HIV should be done in all children with parotid cysts (8).
swelling of the parotid (8). In the HIV population, they are bilateral in up to 80% of cases. Parotid pseudocysts are secondary to viral inflammation and are often the initial manifestation of HIV. Testing for HIV should be done in all children with parotid cysts (8).
Treatment options should be individualized to the patient, with consideration of the risks and benefits of the proposed interventions. Most lymphoepithelial cysts will regress with antiretroviral therapy (5). Only in severe cases of salivary gland dysfunction or disfigurement is surgical intervention appropriate. The approach is cyst aspiration, partial gland excision, or doxycycline sclerotherapy (5). Sclerotherapy may be useful for growth prevention in 75% of cases and for regression of the cyst in only 25% of cases (8).
The diagnostic modality of choice in HIV patients with salivary gland enlargement is computed tomography (CT) or magnetic resonance imaging (MRI). The use of ultrasound in the evaluation of salivary gland enlargement in this population has been proposed as an alternative to conventional imaging and as a good screening tool for malignancy (in lymphoma, which appears solid). Once a malignancy has been ruled out, the management of salivary gland enlargement in the HIV population is watchful waiting (5).
Epstein-Barr Virus (EBV)
Epstein-Barr virus (EBV) infection is a known cause of infectious mononucleosis, which is transmitted through saliva. It also has been implicated in the pathogenesis of certain types of salivary gland tumors in the adult population but not in the pediatric population (9).The adenopathy of mononucleosis can involve periparotid and perisubmandibular lymph nodes.
Chronic Inflammation
The pathogenesis of the chronic salivary inflammatory disease spectrum also has changed with the interplay between sialadenitis, sialectasis, and sialolithiasis. A heterogeneous group of disorders in chronic inflammatory sialadenitis also exist, which include the group of specific and nonspecific granulomatous diseases.
Juvenile Recurrent Parotitis (JRP)
Juvenile recurrent parotitis (JRP), which was formally known as recurrent parotitis of childhood, is the most common inflammatory salivary gland disorder in children in the United States and is second only to mumps worldwide. This condition presents with recurrent inflammation and infection without a definitive etiology. The onset is generally between 3 and 6 years of age, and recurrent episodes continue throughout puberty, when the disease usually resolves. Patients present with pain and edema over the involved gland (often the parotid) and can have systemic symptoms such as fever. On physical exam, patients often have enlarged Stensen’s papilla with associated yellowish plaques of protein coagulum around the opening. Treatment is medical, but sialadenoscopic washout and irrigation has also been described with success (10).
Both flexible and rigid sialadenoscopy have been used for both diagnostic and therapeutic treatment of salivary gland disorders. Small rigid scopes with working ports for saline, antibiotic, or steroid irrigation as well as for balloon dilation are available. One study of 36 patients with JRP showed a 92% recurrence-free rate at 36 months after sialadenoscopic irrigation and steroid infusion (11). Another study of six children had 100% success rate in treating recurrent infections (12). Further research is necessary to further delineate the role of this treatment modality in pediatric salivary gland disease.
Chronic Sialectasis
Chronic inflammation of the salivary glands can lead to ductal dilation, chronic salivary stasis, ascending infections, and parenchymal destruction. It is seen mostly in the adult with a history of childhood recurrent sialadenitis, sialolithiasis, and strictures. The presentation is unilateral, diffuse enlargement of the involved gland with swelling related to eating. Sialography can identify a stricture with proximal ductal dilation. The management includes a spectrum of therapies including ductal dilation or duct incision (if the stricture is distal). Conservative therapy is less effective in management of parotid sialectasis. In this situation, a parotidectomy with facial nerve preservation is required.
Because of the morbidity associated with facial nerve dissection in an inflamed field, alternative modes of therapy have been proposed. The use of botulinum toxin A to modulate parasympathetic stimulation and reduce salivary flow has been reported (13). The theory is that chemical denervation leads to atrophy of parotid gland acini.
Sialolithiasis
Relative to adults, sialolithiasis is a rare condition in the pediatric population. Relatively few cases of pediatric calculus formation in the salivary glands have been reported in the literature. In a review done in 1995, in total, 86 cases were cited. The submandibular glands are the most common site for calculus formation, followed in frequency by the parotid gland. The sublingual glands and the minor salivary glands are rarely affected. Physiologic factors such as alkaline pH, high calcium concentration, and mucin content of the saliva contribute to stone formation. Furthermore, it has been speculated that the tortuosity of Wharton duct with passage of secretions against gravity can promote stasis and calculi (14). The most common presenting symptoms include intermittent, unilateral swelling in the affected gland with ipsilateral pain, all associated with eating.
When an obstruction is suspected, radiography is 90% sensitive. In the past, panoramic and anteroposterior films were used; however, because of bony overlap of the facial
skeleton, these studies are not effective at identifying calculi. Axial CT scans are useful in identifying radiopaque sialoliths. The majority of stones can be found along the course of the ducts (Stensen’s or Wharton duct) (14) with a rare occurrence of intraparenchymal stones. Most submandibular gland calculi are radiopaque, while a significant majority of parotid stones are radiolucent. Nonopaque sialoliths can be identified with ultrasonography and, in particular, color Doppler ultrasonography (15).
skeleton, these studies are not effective at identifying calculi. Axial CT scans are useful in identifying radiopaque sialoliths. The majority of stones can be found along the course of the ducts (Stensen’s or Wharton duct) (14) with a rare occurrence of intraparenchymal stones. Most submandibular gland calculi are radiopaque, while a significant majority of parotid stones are radiolucent. Nonopaque sialoliths can be identified with ultrasonography and, in particular, color Doppler ultrasonography (15).
The underlying pathophysiology leading to stone formation is stasis secondary to either duct obstruction, decreased saliva production, or a side effect of pharmacotherapy. The most common etiology of chronic duct obstruction is mucous plugging with deposition of calcium salts. Accidental biting of Stensen’s duct also can contribute to duct stricture and stasis. Decreased salivary production due to autoimmune disease is less commonly encountered in the pediatric population.
The aim of management of sialolithiasis is to restore the normal parenchymal architecture of the gland and allow its long-term functional recovery. A conservative and mostly effective mode of therapy includes stimulation of saliva production by instructing the child to suck on acidic sialogogues. In children, submandibular stones have been reported to pass out of the duct spontaneously after this maneuver. Spontaneous passage of parotid stones is less likely because of the pathway of Stensen’s duct through the buccinator muscle (15).
If conservative treatment fails, alternative modes of therapy include duct dilation, sialolithotomy, or sialadenectomy. The latter is indicated if the stone is located in the posterior third of the gland or when damage to the parenchyma of the gland results in a nonfunctional gland. To evaluate this, radiographic imaging including sialography, scintigraphy, ultrasonography, and MRI can be used.
Because of the potential morbidity associated with sialolithotomy and sialadenectomy, a less invasive mode of therapy has been recently proposed. Extracorporeal electromagnetic shockwave lithotripsy (EESWL) has improved the nonsurgical approach to treatment of salivary gland calculi (15). In their report of seven patients treated with noninvasive EESWL, Ottaviani and colleagues reported complete stone disintegration in 71% of the patients and 29% partial resolution. EESWL therapy is instituted after resolution of the acute inflammatory state with antibiotics and antiinflammatory agents. Symptom relief was observed in all patients who were studied. After an average of five sessions, all but one had complete functional recovery of the gland, as observed on scintigraphy (15). McJunkin et al. (16) recently described a case of treatment of a 2-cm parotid sialolith with a single session of lithotripsy with complete resolution.
Cysts
Mucous retention cysts are epithelium-lined cysts that result from duct obstruction. Mostly seen in the sublingual gland and presenting similar to a ranula, these true cysts involve the minor salivary glands. A ranula, in contrast, is not a true epithelium-lined cyst and represents a collection of extravasated mucin. Plunging ranulas extend below the mylohyoid muscle and can be first seen with a cervical or intraoral neck mass or both. Management is by marsupialization or excision, often in association with removal of the sublingual gland (3).
Granulomatous Lesions
Chronic salivary gland enlargement may be due to granulomatous inflammation resulting in a nodularity to the gland that must be differentiated from a neoplastic process. Tuberculosis, sarcoidosis, histoplasmosis, tularemia, cat-scratch disease, and toxoplasmosis have all been reported (3).
SALIVARY GLAND NEOPLASMS
Neoplasms of salivary gland origin are relatively uncommon in the pediatric population. They comprise 8% of all pediatric head and neck tumors, representing the fourth most frequent, after neoplasms of the nasopharynx, skin, and thyroid (17). The histologic pattern of the tumors seen in the pediatric versus adult populations is the same; however, the rate of occurrence of each subtype is different in these groups. Approximately 15% to 25% of all salivary gland tumors are malignant in adults, whereas in the pediatric population, this rate is higher, approaching 50% when vascular neoplasms are excluded (17). When including the vascular tumors in these statistics, about 35% of all salivary gland lesions in children are malignant. Thus, a solid mass identified in a child has a 2.5-fold higher rate of malignancy in comparison to a solid mass identified in an adult. Salivary gland neoplasms can be classified into benign (including the vascular lesions) and malignant tumors. The latter are subclassified into low-grade and high-grade malignancies based on histology.
Benign Mesenchymal Tumors
Benign salivary gland tumors may be of nonepithelial or epithelial origin. The mesenchymal lesions include hemangiomas (73.5% of nonepithelial tumors), lymphatic vascular malformations (18.5%), neurogenic tumors (4.2%), lipomas (1.5%), and the rarer lesions xanthoma and fibromatosis (18).
Hemangiomas account for approximately 50% to 60% of neoplasms seen in the pediatric population (19). These are nonencapsulated, often infiltrating lesions that are composed of solid masses of cells and multiple anastomosing capillaries replacing the acinar structure of the gland, while not affecting the ductal structures or the facial nerve. They appear spongy and lobulated, with a purple blush. The distribution of hemangiomas among the various salivary glands is as follows: 80% occur in parotid, 18% in the submandibular glands, and 2% in minor salivary glands
(19). Two types of hemangiomas are encountered: The capillary form is rapidly growing, present at birth, and often regresses by the age of 1 year. The cavernous form is more aggressive, appears in the older child, and has a tendency to bleed and deform. This hemangioma subtype is more difficult to manage.
(19). Two types of hemangiomas are encountered: The capillary form is rapidly growing, present at birth, and often regresses by the age of 1 year. The cavernous form is more aggressive, appears in the older child, and has a tendency to bleed and deform. This hemangioma subtype is more difficult to manage.
The capillary hemangiomas are more commonly seen in girls, either at birth or in the first few months of life. Clinical diagnosis is the rule, and the course of resolution is almost predictable (albeit controversial) with conservative management. Cavernous hemangiomas are initially seen later in life. Diagnosis of salivary hemangiomas is mostly based on physical examination. Hemangiomas involving the salivary glands, specifically the parotid area, can be quite deforming. They are usually confined to the intracapsular region and may extend to the overlying skin. Ultrasound imaging may be helpful in differentiating this vascular lesion from a cystic mass but cannot define the extent of the disease. In unusual cases, an MRI may be obtained. This radiographic modality is diagnostic and can help define the limits of the mass.
Treatment of hemangiomas is not necessary if the mass is small and not involving critical organs or affecting function. In general, spontaneous involution occurs by age 4 to 6 years. In certain instances, a trial of prednisone, 3 to 5 mg/kg/day for several weeks, may serve as an effective initial course of treatment (19). A treatment protocol does not exist, but a study examining 1,109 cases of cutaneous hemangiomas (including head and neck lesions) suggested that systemic corticosteroids are effective in 36% of patients, independent of dosage, pharmacologic agents, and duration of therapy (ranging from 7 weeks with conventionaldose prednisolone regimen to 35 days of high-dose methylprednisolone regimen). According to this report, the dimension of the lesion and age at initiation of treatment are important factors affecting response to treatment. Furthermore, the authors cited a 21% rebound growth after discontinuation of systemic therapy (20). It is important to recognize that long-term systemic corticosteroid therapy is not benign. The efficacy of therapy should be questioned if no response is seen within several weeks of therapy, as systemic complications are well recognized. The indications for surgical intervention in young patients with hemangiomas are increase in tumor size, rapid tumor growth, failure of tumor to involute, and hemorrhage into the lesions.
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