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Significance

Salivary gland disorders are not a major public health problem in the Western world.

Neoplasms of the salivary glands account for fewer than 3% of tumors in the US and only 6%

of head and neck neoplasms.

Salivary gland tumors in children are uncommon, but the frequency of malignant tumors is

higher in children than in adults. (For more information, see Medscape Reference article

Malignant Parotid Tumors.) All masses in children require thorough diagnostic evaluation.

Benign masses of the parotid gland in children may be due to vasoformative abnormalities,

cysts, inflammatory processes, or neoplasms. The most common intraparotid mass is the

benign lymph node, as a significant number of lymph nodes are present in the parotid. The

most common benign tumor in children is thehemangioma.Of the benign epithelial tumors,

the mixed tumor (pleomorphic adenoma) is the most common.

Anatomi

The parotid gland is the largest of the major salivary glands. It arises as an epithelial

proliferation from the lining of the oral cavity at 5 weeks postovulation. It lies in the

preauricular region deep to the skin and subcutaneous tissue. The facial nerve (cranial nerve

VII) divides the gland into the larger superficial and smaller deep component. Though these

are commonly referred to as the superficial and deep lobes, they are not true lobes.

The parotid duct (Stensen duct) courses from the anterior border of the parotid gland below

the zygoma, crosses the masseter muscle and the buccal fat pad, and turns deep to penetrate

the buccinator muscle, finally opening intraorally at a papilla opposite the second upper

molar. The duct varies in length from 4.0-7.0 cm. The parotid tail extends inferiorly into theneck as low as the sternocleidomastoid muscle. Acinar cells of the parotid gland are primarily

secretory and produce thin, watery saliva devoid of mucous.

Incidence and Etiology

Approximately 2500 new cases of salivary gland neoplasms are diagnosed each year. Parotid

neoplasms account for 80% of salivary neoplasms. Of parotid masses, 75% are neoplastic;

the remaining 25% are nonneoplastic infiltrative processes, such as cysts and inflammation.

Of parotid neoplasms, 70-80% are benign. Except for Warthin tumors, benign tumors of the

parotid gland are more likely to occur in women than in men. The median age for occurrenceof these tumors is in the fifth decade of life. Parotid tumors occur most commonly in

Caucasians. The etiology of these tumors is unknown, but the possibility of an adenoma gene

currently is under investigation for its involvement in the development of pleomorphic

adenomas. The most common benign parotid tumor in children is the mixed tumor.

History and Physical Examination

A thorough history and physical examination is important in the workup of parotid masses.

The major goal in the evaluation is to determine or exclude the diagnosis of malignancy.

History often is the most useful tool in distinguishing inflammatory from neoplastic masses.

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Characteristics of inflammatory conditions are sudden onset, pain, and systemic infection.

The most common presentation is that of an asymptomatic mass (81%) noted incidentally

while washing or shaving the face.[1] Pain (12%) orfacial nerve paralysis(7%) is less

frequent. Facial nerve paralysis is more commonly due to malignancy in the presence of a

parotid mass, but most facial nerve paralysis is due toBell palsy.Parotid masses occur most

commonly in the lower pole, or tail, and in the superficial lobe of the gland.

Physical examination most often reveals a mobile nontender mass that is firm and solitary.

Evaluate the possibility of a deep tumor by intraoral examination, with attention directed to

the tonsillar fossa and soft palate. Inspect the Stensen duct for the character of the salivary

flow (clarity, consistency, purulence) and notation of redness, bulging, and irritation of the

ductal orifice as part of the physical examination. Evaluate the skin, oral cavity, oropharynx,

and neck for possible primary lesions or nodal disease.

Diagnosis

Laboratory studies

Hematologic and serologic tests are of little importance in the workup of salivary gland

tumors.

Radiologic studies

Radiologic studies are involved minimally in the workup of an asymptomatic mass.

Plain radiography findings can help the clinician exclude calculi. Sialography is rarely used. When used, it helps the clinician delineate disorders of ductal

function or anatomy.

CT scan is almost 100% sensitive in detecting a salivary gland mass, but it cannot help theclinician differentiate between a benign and a malignant mass. It is most helpful in specifying

the size and anatomic extent of a tumor.

MRI is superior in demonstrating benign tumors of the parotid gland because of its greatercontrast than CT scan.

Positron emission tomography (PET) scans may be of value in assessing malignant tumors,with attention to metastatic adenopathy and distant metastases.

Biopsy

Fine-needle aspirationmay be a valuable pretreatment diagnostic test. Its overall accuracy is

greater than 96%, with a sensitivity for benign tumors of 88-98% and a specificity of 94%. Its

sensitivity for detecting malignant tumors ranges from 58-96%, and its specificity is 71-88%.

Frozen sections are 93% accurate when performed at surgery, but their use is controversial,

since diagnosis depends on the experience of the pathologist with regard to salivary gland

tumors.

The standard biopsy approach is a superficial parotidectomy with preservation of the facial

nerve. For 80-90% of parotid neoplasms, this procedure is both diagnostic and therapeutic.

For this reason, preoperative fine-needle aspiration biopsy is recommended, since it can

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change the clinical approach in up to 35% of patients.[2] Lymph nodes can be enucleated,[3] as

can Warthin tumors, andsialadenitisdoes not require surgical intervention in most cases.

Classification

Table 1. Classification of Benign Primary Epithelial Salivary Gland Tumors(Open Table in a

new window)

Mixed tumor (pleomorphic adenoma)

Warthin tumor (papillary cystadenoma lymphomatosum)

Oncocytoma

Monomorphic tumors

Sebaceous tumors

Benign lymphoepithelial lesion

Papillary ductal adenoma (papilloma)

Unclassified

Benign pleomorphic adenoma or benign mixed tumor

Most common parotid neoplasm (80%)[4] Proliferation of epithelial and myoepithelial cells of the ducts and an increase in stromal

components

Slow growing, lobular, and not well encapsulated Recurrence rate of 1-5% with appropriate excision (parotidectomy) Recurrence possibly secondary to capsular disruption during surgery Malignant degeneration occurring in 2-10% of adenomas observed for long periods, with

carcinoma ex-pleomorphic adenoma occurring most frequently as adenocarcinoma

Warthin tumor (papillary cystadenoma lymphomatosum or adenolymphoma)

Second most common benign parotid tumor (5%) Most common bilateral benign neoplasm of the parotid Marked male as compared to female predominance Occurs later in life (sixth and seventh decades) Presents as a lymphocytic infiltrate and cystic epithelial proliferation May represent heterotopic salivary gland epithelial tissue trapped within intraparotid lymph

nodes

Incidence of bilaterality and multicentricity of 10% Malignant transformation rare (almost unheard of)

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Oncocytoma

Accounts for 1% of salivary gland tumors Composed of large oxyphilic cells (oncocytes) May be multiple

Monomorphic tumors

Rare, usually epithelial in origin

Treatment & Management

Superficial parotidectomy is the treatment of choice for most benign tumors in the superficial

lobe. Make every effort to preserve the facial nerve. In order to preserve the facial nerve, it is

important to try to determine the proximity of the nerve to the capsule of the tumor prior to

surgery. Results of a retrospective review showed that malignant tumors were likely to have apositive facial nerve margin.[5]

Avoid enucleation (except for Warthin tumors and lymph nodes), since it greatly increases

the likelihood of recurrence (up to 80%) and nerve damage. Deep lobe tumors demand total

parotidectomy with preservation of the facial nerve. For recurrences, postoperative

radiotherapy may be administered, with local control rates exceeding 95%.

Surgical incision

Parotidectomy incision should allow for adequate exposure and the most aesthetic result. The

incision begins anterior to the superior root of the helix and descends anterior to the tragus. Itthen is directed behind the lobule of the pinna and can be carried down anteriorly onto the

neck as dictated by the need for exposure.

If a large soft tissue defect is created by the excision of the parotid tumor, numerous

autologous or allograft tissues (ie, dermal grafts, fascial grafts, fat grafts, AlloDerm) or

synthetic substances may be used for filling these defects. Try to preserve a layer of tissue

(the parotid fascia or SMAS layer) if it does not compromise the capsule of the tumor. This

preservation is important so that a layer of tissue interposes between the cut salivary tissue

and the skin. This has been shown to reduce the incidence of Frey syndrome (gustatory

sweating).

Complications

Parotidectomy can be performed with little morbidity and no mortality. Most serious

complications result from damage to the facial nerve (either temporary or permanent

paralysis). Injury to the greater auricular nerve results in hypesthesia of the ear. A slight loss

of fullness and an increased prominence of the angle of the mandible may occur after

superficial parotidectomy. Uncommon sequelae include salivary fistula, seroma, hematoma,

and infection.

Frey (auriculotemporal) syndrome results from aberrant regeneration of auriculotemporalnerve fibers to sweat glands in the skin. The result is sweating on the affected side of the face

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during mastication. The incidence of this complication is variable, depending upon whether

the examiner performs a starch-iodine test. Its incidence may be decreased by interposing a

layer of tissue (either preserving the SMAS layer and replacing it on the surface of the parotid

gland before closing the incision or placing a layer of allograft in a similar position)

1. Byrne MN, Spector JG. Parotid masses: evaluation, analysis, and currentmanagement.Laryngoscope. Jan 1988;98(1):99-105.[Medline].2. Heller KS, Dubner S, Chess Q, Attie JN. Value of fine needle aspiration biopsy of

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3. Ascani G, Messi M, Balercia P. [Surgical management of pleomorphic adenoma ofthe salivary glands: our experience]. G Chir. Aug-Sep 2008;29(8-9):343-6.[Medline].

4. Kubiak M, Lapienis MM, Kaczmarczyk D, Morawiec-Sztandera A. [Surgerytreatment of salivary gland tumors]. Otolaryngol Pol. 2008;62(5):567-73.[Medline].

5. Domenick NA, Johnson JT. Parotid tumor size predicts proximity to the facial nerve.Laryngoscope. Nov 2011;121(11):2366-70.[Medline].

6. Greenfield LJ, Mulholland M, Oldhan KT. Head and neck. In: Surgery: ScientificPrinciples and Practice. 1997:635-51.

7. Johnson JT, Kohut RI, Pillsbury HC.Head and Neck Surgery-Otolaryngology.1993:447-83.

8. OBrien JC. Head and neck I: Tumors. Selected Readings in Plastic Surgery. 2000;9(9):30-42.

9. Rodriguez-Bigas MA, Sako K, Razack MS, et al. Benign parotid tumors: a 24-yearexperience.J Surg Oncol. Mar 1991;46(3):159-61.[Medline].

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