Benign Tumors of Minor Salivary Glands Clinical Presentation

Updated: Nov 28, 2017
  • Author: Vijay A Patel, MD; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Presentation

Physical Examination

Patients with salivary gland lesions require a thorough head and neck evaluation. Cranial nerve function is carefully noted and documented. Careful attention is given to findings that may indicate malignancy, such as the following:

  • Rapid growth
  • Fixation to adjacent structures
  • Associated cervical adenopathy
  • Pain
  • Paresthesias
  • Ulceration
  • Cranial nerve involvement

Most patients who have benign minor salivary gland tumors present with a painless, progressive, enlarging mass in the affected minor salivary gland or oral cavity mucosal space. These masses can be firm to hard on palpation, mobile if within the salivary gland, and fixed in cases of local invasion. [13]  Because of the multiple and varied locations of minor salivary glands, the presentation of benign tumors may be less specific.

Paranasal sinus minor salivary gland neoplasms may cause obstructive sinusitis, epistaxis, and nasal obstruction. Laryngotracheal salivary gland neoplasms may give rise to hoarseness, dysphagia, odynophonia, and cough. Parapharyngeal space salivary neoplasms often are diagnosed late in their evolution given lack of presenting symptoms until a large tumor size has been attained. Trismus, dysphagia, or dysphonia may be the first indication of a tumor in the parapharyngeal space.

Most sources cite the palate as the most common anatomic site for minor salivary gland tumors, of which 42-75% occur in the palatal mucosa. Other sites include the lips (4-21%), the buccal mucosa (5-16%), the tongue or floor of the mouth (4-12%), and the retromolar area (3-7%). [14]

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Classification

Basal cell adenoma

Basal cell adenoma, first described by Kleinsasser and Klein in 1967, is an epithelial neoplasm composed of cells with a basaloid appearance and without a chondromyxoid matrix. [15]  It accounts for 1-3% of all salivary neoplasms and typically occurs in adults, usually in the fourth to seventh decades. Most of these lesions (75-80%) occur in the parotid gland; the rest involve the submandibular and minor salivary glands, especially the upper lip and buccal mucosa. Basal cell adenoma typically presents as a slowly enlarging, asymptomatic mass. [16]

The membranous variant of basal cell adenoma, also known as a dermal analogue tumor, is associated in 25-38% of cases with Brooke-Spiegler syndrome, an autosomal dominant condition characterized by numerous dermal cylindromas, trichoepitheliomas, spiradenomas, or combinations thereof. [17]

Canalicular adenoma

Canalicular adenoma is defined as a tumor composed of columnar epithelial cells arranged in thin, anastomosing cords with a beaded pattern. It typically occurs in patients older than 50 years (range, 33-87 years), with a female-to-male ratio of 1:1 to 1.8:1. [18]  It most commonly affects the upper lip (80% of cases) but has also been found to involve the buccal mucosa (10%), palate (3-10%), and parotid gland (<4%). [19]

Canalicular adenoma typically presents as a painless, slowly enlarging submucosal mass covered by intact mucosa that ranges in color from normal to slightly blue, often mimicking a mucocele. Although it is typically a solitary lesion, multiple clinically apparent tumors have also been described. [20]

Cystadenoma

Cystadenomas constitute a rare category of benign cystic neoplasms. These tumors predominantly occur in the fifth decade, with a female-to-male ratio of 2:1 to 3:1. [16]  They typically are found in the parotid gland and submandibular gland, though they may also be found in the lip. Oncocytic cystadenomas are common in the minor salivary tissue of the larynx as well. [21]  Cystadenomas usually present as fluctuant painless masses on physical examination. In the oral cavity, they can also mimic the clinical presentation of mucoceles.

Lymphadenoma

Lymphadenomas are rare benign tumors with prominent lymphoid stroma that does not consist of an oncocytic bilayer, as seen in Warthin tumor. This group of tumors usually occurs after the fifth decade, with no predilection for either sex. [22]  Lymphadenoma is essentially a condition of the parotid gland, though rare cases involving the minor salivary glands have been reported. Lymphadenomas typically present as slow-growing painless masses; some degree of cystic change may result in a fluctuant appearance. [16]

Myoepithelioma

Myoepitheliomas are uncommon tumors, comprising no more than 1-2% of all salivary neoplasms. The majority are benign (70-90%), but some are malignant (10-30%). Approximately 75% of all cases occur in the parotid gland and palate. They are uncommon in the submandibular gland and have been described infrequently in a variety of other sites, including the sinonasal tract, oral cavity, and larynx.

Myoepithelioma affects both sexes equally and most commonly occurs between the ages of 40 and 50 years (range, 9-95 years). The tumor often presents as a mass that enlarges slowly over a period of several months to years. [16]

Necrotizing sialometaplasia

Necrotizing sialometaplasia is a reactive nonneoplastic inflammatory process that usually affects the minor salivary glands of the palate; however, it may involve minor salivary glands in any location. It can easily be mistaken for a malignant tumor, in that it presents as a single unilateral painless (or only slightly painful) lesion of the hard palate.

Necrotizing sialometaplasia is of unclear origin but is thought to result from vascular infarction of salivary gland lobules. Potential causes of diminished blood flow include the following:

  • Trauma
  • Local anesthetic injection
  • Smoking
  • Diabetes mellitus
  • Vascular disease
  • Pressure from dentures

Necrotizing sialometaplasia affects patients between the ages of 23 and 66 years and is two to three times more common in males than in females. Lesions usually appear as large (1-4 cm), painless or painful, deeply ulcerated areas lateral to the palatal midline and near the junction of the hard and soft palates. They are usually unilateral but may be bilateral in some cases. A biopsy assists in ruling out a malignant process; otherwise, no additional treatment is indicated.  [23]

Oncocytoma

Duplay first described an oncocytic tumor in 1875. Like other oncocytic neoplasms, oncocytoma is a tumor of the elderly, most commonly occurring in the seventh and eighth decades of life, with no predilection for either sex. [16]  In 20% of cases, a prior history of irradiation may be present, giving rise to a subpopulation that presents at a younger age. [24]

More than 80% of oncocytomas occur in the parotid gland, though they can occur in the submandibular and minor salivary glands as well. These tumors are typically slow-growing painless masses; 7% of patients are found to have bilateral lesions. Oncocytomas may recur if excision is incomplete. [25]

Pleomorphic adenoma

Pleomorphic adenoma is the most common salivary gland tumor, accounting for 45-60% of all benign and malignant salivary neoplasms. [26] Approximately 80% occur in the parotid gland, 15% in the submandibular gland, and 10% in the minor salivary glands. In the oral cavity, the most commonly affected site is the palate, followed by the upper lip and the buccal mucosa. [27]  These lesions are more frequent in women and occur in all age groups (mean age, 45 years).

The majority of pleomorphic adenomas grow slowly and are relatively asymptomatic, but they can reach an extremely large size if neglected. These tumors were termed pleomorphic because of the epithelial and connective-tissue components that compose them in varying degrees. Their gross appearance is that of a round, smooth mass with a thin, delicate, incomplete capsule. Notably, pleomorphic adenomas that arise in the minor salivary glands usually lack a capsule.

Sialolipoma

A sialolipoma is characterized as a well-circumscribed mass consisting of salivary gland and mature adipose tissue. It remains unclear whether the salivary tissue within the lesion is neoplastic tissue, hamartomatous tissue, or residual entrapped glandular tissue. Although sialolipomas are most commonly seen in the parotid gland, they can also involve the minor salivary glands and may affect the hard or soft palate. Such lesions should be distinguished from normal fatty replacement of salivary glands, which can occur with the aging process. [28]

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