Salivary Gland Enlargement

The major salivary glands are the paired parotid, submandibular, and sublingual glands. There are approximately 1,000 minor salivary glands throughout the upper aerodigestive tract, including those in the palate, oropharynx, hypopharynx, larynx, trachea, and middle ear. Most diseases may affect the major salivary glands and are the focus of this chapter.

MEDICAL HISTORY AND PHYSICAL EXAMINATION

The primary disorders of the major salivary glands mandate taking a thorough history to establish a differential diagnosis (Table 25-1) that varies from inflammatory to neoplastic and acquired to developmental disorders. A full medical history is necessary to determine whether infectious, metabolic, endocrinologic, and collagen vascular diseases may have a salivary gland manifestation (see below).

The medical history is enhanced by a thorough physical examination with particular attention to palpation and inspection. The ductal orifices of the salivary glands should be inspected, and the consistency and rate of salivary flow should be assessed. Bimanual palpation (one hand inside the mouth and the other outside) is particularly helpful in identifying abnormalities within the ducts and deep portions of the glands. Palpation along the duct may allow identification of a stone.

Changes in adjacent structures can mimic salivary gland enlargement. Hypertrophy of the masseter muscle, which is anterior and deep to the parotid gland, may be idiopathic or caused by excessive grinding of the teeth and can appear as a parotid mass. Mandibular masses can simulate either a parotid or a submandibular mass. Other lesions, such as lipoma or lymphadenopathy, can also occur in the region. In addition, prominent transverse process of C2 may be mistaken for a parotid mass.

ANCILLARY DIAGNOSTIC TESTS

Selective diagnostic tests are useful in the assessment of salivary gland disease. Plain radiography is perhaps the simplest method to identify a calcified calculus. Calcified stones are most often found in the submandibular gland and its duct; radiolucent stones are more common in parotid disease. Occlusal (bite) radiographs are obtained at the dentist’s office and provide a quick and simple method of diagnosing a submandibular duct stone.

Computed tomography can be used to confirm the presence of a stone if plain radiography is not revealing. During an acute inflammatory state, computed tomography scan can help identify a stone and/or the presence of an abscess that may require drainage. Magnetic resonance imaging is particularly helpful in identifying masses of the deep lobe of the parotid gland (underneath the facial nerve), or parapharyngeal space lesions that may present as parotid masses.

TABLE 25-1. History and physical examination

1.	Localization: Is the problem localized to one major salivary gland, or does it also affect the contralateral gland or other salivary glands?
2.	Duration: Has the disorder been present for days, weeks, months, or years?
3.	Pain and tenderness: Is the area of involvement tender to palpation, and is the pain localized or diffuse?
4.	Course of disease: Is the disorder recurrent? If so what is the interval of recurrence? Is the disease progressive, or has it been relatively static?
5.	Associated symptoms and signs: Is there fever, dysphagia, halitosis, facial nerve paresis, or paralysis? Does the swelling cause trismus?

Fine-needle aspiration biopsy may be useful for cytologic diagnosis of a salivary gland mass. The accuracy and true value of this technique depend heavily on the skill and experience of the cytopathologist interpreting the findings and on the judicious use of the results by the clinician. Unfortunately, needle biopsy may not be able to differentiate benign from malignant epithelial tumors.

Radioisotope scanning is not routinely performed except to confirm a diagnosis of Warthin’s tumor or oncocytoma (benign salivary tumors) in patients who are high risk for surgery. These tumors have abundant oncocytes, which tend to concentrate technetium.

Other tests include a white blood cell count for patients with an acute inflammatory process. Culture of the suppurative saliva may be helpful in identifying the specific bacterial organism. If mumps is suspected, a viral titer is useful. Serologic tests for collagen vascular and rheumatoid disease may be helpful. A chest radiograph should be obtained when the possibility of sarcoidosis, lymphoma, or tuberculosis is being considered. In cases of diffuse disorders such as Sjögren’s syndrome, biopsy of the minor salivary glands of the lower lip may be diagnostic in as many as 75% of patients.

INFLAMMATORY DISORDERS

Acute Suppurative Sialadenitis

Acute suppurative sialadenitis may affect any of the major salivary glands. Acute bacterial parotitis usually occurs among debilitated patients who are dehydrated and have poor oral hygiene (Fig. 25-1). It occurs classically among dehydrated postoperative patients with a nasogastric tube. The patient often has an elevated temperature, acute swelling, and tenderness of the involved gland with overlying erythema and edema. Purulent (Stensen’s) ductal secretions often are present. The most common organism is Staphylococcus aureus. However, a variety of other organisms can be present among immunocompromised patients. Treatment is aimed at hydration, intravenous antimicrobial
therapy (most often antistaphylococcal), sialogogues (such as citrus candy to encourage salivary flow), warm compresses, and analgesics. Since the parotid gland is enveloped with a thick fascia, abscess formation may not be appreciated early enough. Therefore, CT scan is indicated if the infection does not respond to treatment.