eMedicine Specialties > Plastic Surgery > Head/Neck

Parotid Tumors, Benign

Sanford Dubner, MD, Assistant Clinical Professor, Department of Surgery, Long Island Jewish Medical Center, Albert Einstein College of Medicine

Updated: Nov 20, 2008

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 eMedicine article Parotid Tumors, Malignant.) 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 the hemangioma. Of the benign epithelial tumors, the mixed tumor (pleomorphic adenoma) is the most common.

For information on hemangioma and other dermatologic disorders in children, visit Medscape's Pediatric Dermatology Resource Center.

Anatomy

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 the neck 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 occurrence of 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.

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%) or facial 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 to Bell 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 the clinician 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 greater contrast 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 aspiration may 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 change the clinical approach in up to 35% of patients.² Lymph nodes can be enucleated,³ as can Warthin tumors, and sialadenitis does not require surgical intervention in most cases.

Classification

Classification of Benign Primary Epithelial Salivary Gland Tumors

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)

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

Superficial parotidectomy is the treatment of choice for most benign tumors in the superficial lobe. Make every effort to preserve the facial nerve. 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. It then 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 auriculotemporal nerve fibers to sweat glands in the skin. The result is sweating on the affected side of the face 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).

References

1. Byrne MN, Spector JG. Parotid masses: evaluation, analysis, and current management. Laryngoscope. Jan 1988;98(1):99-105. [Medline].

2. Heller KS, Dubner S, Chess Q, Attie JN. Value of fine needle aspiration biopsy of salivary gland masses in clinical decision-making. Am J Surg. Dec 1992;164(6):667-70. [Medline].

3. Ascani G, Messi M, Balercia P. [Surgical management of pleomorphic adenoma of the 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. [Surgery treatment of salivary gland tumors]. Otolaryngol Pol. 2008;62(5):567-73. [Medline].

5. Greenfield LJ, Mulholland M, Oldhan KT. Head and neck. In: Surgery: Scientific Principles and Practice. 1997:635-51.

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

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

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

9. Thawley SE, Panje WR, Batsakis JG. Comprehensive Management of Head and Neck Tumors. 1987:1042-138.

Keywords

parotid tumor, benign parotid tumor, salivary gland tumors, salivary gland disorders, parotid gland, lymph nodes, benign lymph node, lymph node mass, hemangioma, benign epithelial tumor, mixed tumor, pleomorphic adenoma, major salivary gland, major salivary gland tumor, salivary gland neoplasm, parotid neoplasm, parotid mass, Warthin tumor

Contributor Information and Disclosures

Author

Sanford Dubner, MD, Assistant Clinical Professor, Department of Surgery, Long Island Jewish Medical Center, Albert Einstein College of Medicine
Sanford Dubner, MD is a member of the following medical societies: American College of Surgeons, American Head and Neck Society, American Society of Plastic and Reconstructive Surgery, and New York Head and Neck Society
Disclosure: Nothing to disclose.

Medical Editor

Lawrence Ketch, MD, FAAP, FACS, Head, Program Director, Associate Professor, Department of Surgery, Division of Plastic Surgery, University of Colorado Health Sciences Center; Chief, Pediatric Plastic, The Children's Hospital of Denver
Lawrence Ketch, MD, FAAP, FACS is a member of the following medical societies: American Academy of Pediatrics, American Association for Hand Surgery, American Association of Plastic Surgeons, American Burn Association, American Cleft Palate/Craniofacial Association, American College of Surgeons, American Society for Surgery of the Hand, American Society of Maxillofacial Surgeons, American Society of Plastic Surgeons, Association for Academic Surgery, and Plastic Surgery Research Council
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Jaime R Garza, MD, DDS, FACS, Consulting Staff, Private Practice
Jaime R Garza, MD, DDS, FACS is a member of the following medical societies: Alpha Omega Alpha, American Academy of Otolaryngology-Head and Neck Surgery, American Cleft Palate/Craniofacial Association, American College of Surgeons, American Medical Association, American Society for Aesthetic Plastic Surgery, American Society of Maxillofacial Surgeons, Texas Medical Association, and Texas Society of Plastic Surgeons
Disclosure: Nothing to disclose.

CME Editor

Nicolas (Nick) G Slenkovich, MD, Practice Director, Colorado Plastic Surgery Center at Swedish Medical Center
Nicolas (Nick) G Slenkovich, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Medical Association, American Society of Aesthetic Plastic Surgery, American Society of Plastic Surgeons, and Colorado Medical Society
Disclosure: Nothing to disclose.

Chief Editor

Deepak Narayan, MD, FRCS, Associate Professor of Surgery (Plastic), Yale University School of Medicine; Chief of Plastic Surgery, West Haven Veterans Affairs Medical Center
Deepak Narayan, MD, FRCS is a member of the following medical societies: American Association for the Advancement of Science, American College of Surgeons, American Medical Association, American Society of Maxillofacial Surgeons, American Society of Plastic Surgeons, Indian Medical Association, Plastic Surgery Research Council, Royal College of Surgeons of Edinburgh, and Royal College of Surgeons of England
Disclosure: Nothing to disclose.

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors Ashley D Gordon, MD, and Richard E Kirschner, MD, to the development and writing of this article.

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