Salivary Gland Tumors

Neoplasms of the salivary glands comprise a small percentage of head and neck tumors.

Types of tumor

The parotid glands are the largest and are bilateral pre- and infra-auricular structures. The submandibular glands and the sublingual glands are similarly paired and lie below the mandible and in the floor of the mouth, respectively. The minor glands are scattered throughout the upper aerodigestive tract along the mucosal surfaces.

1. Pleomorphic adenoma (benign mixed tumor);

a. the most common benign tumor of all of the salivary glands.

b. typically, it is a firm, mobile, asymptomatic mass and has a pseudocapsule.

c. these lesions require adequate excision initially or they recur and can become locally invasive.

d. for lesions of the lateral lobe, superficial parotidectomy is the accepted treatment.

2.Warthin’s tumor (cystadenolymphomatosum);

a. a cystic tumor that occurs primarily in the parotid glands

b. men over 40 years of age

c. it can be bilateral in 10% to 15% of patients.

d. lateral parotidectomy is adequate treatment.

3.Necrotizing sialometaplasia;

a. a benign condition,

b. most commonly presenting on the palate (as an ulcerative mass)

c. it is thought to be a metaplastic reaction to local ischemia.

d. the significance of this lesion is that it looks grossly malignant and

histologically can mimic salivary malignancies.

e. unlike its malignant counterparts, necrotizing sialometaplasia resolves

without aggressive treatment.

4.Mucoepidermoid carcinoma;

a. the most common malignant tumor of the major salivary glands.

b. it is highly differentiated and relatively nonaggressive.

5.Adenoid cystic carcinoma ;

a. the most common minor salivary gland malignancy.

b. this unusual tumor spreads perineurally, by direct invasion, or

hematogenously.

c. the tumor can recur after many years of disease-free survival.

6.Malignant mixed tumor;

a. a highly malignant tumor that metastasizes early to the neck.

b. it can occur de novo or as a degenerative lesion within a longstanding benign mixed tumor.

7.Squamous cell carcinoma,

8.Adenocarcinoma,

9.AIDS-related lymphoepitheliomas,

10.Lymphoma

Diagnosis

a. a thorough history

b. physical examination

c. a fine-needle aspiration biopsy and cytologic evaluation

All salivary gland tumors need to be removed regardless of the above findings.

The only salivary gland tumors that do not require excision are AIDS-related benign tumors and lymphomas.

Treatment

Treatment of salivary gland tumors is straightforward: remove the gland(s) containing the tumor. With respect to the parotid, the lateral or superficial lobe is dissected from the facial nerve and removed, thus providing access to deep lobe tumors. Malignant tumors require excision of the deep lobe as well, but benign tumors are sufficiently treated by lateral parotidectomy.

Prognosis

The prognosis for benign salivary tumors is excellent, if they are adequately removed.

Intraoral Tumors

The incidence of this disease varies greatly from one part of the world to another; it accounts for 5% of all cancers in the United States and 50% in India. This difference is the result of cultural variations (e.g., the excellent oral hygiene in the United States, the high incidence of denture wearing and dental caries in the United Kingdom, and the betel chewing of India).

Etiologic Factors

1. tobacco

2. alcohol

3. denture wearing

4. poor oral hygiene

5. Plummer-Vinson syndrome

(iron deficiency results in atrophic intraoral mucosal changes)

Pathology

Intraoral malignant lesions;

1. 1. squamous carcinoma (more than 90%)

2. melanoma

3. lymphoma

4. sarcoma

Leukoplakia

Leukoplakia, (literally “a white patch,”)

1. thickening of the superficial mucosal layer.

2. the incidence of in situ carcinoma was 1.8% and invasive carcinoma 8.1%

Squamous Cell Carcinoma

1. typically an ulcerated lesion with indurated edges.

2. it may project from the surface (exophytic) or infiltrate deeply (endophytic).

Metastatic Lesions

Intraoral cancer metastasizes to neck nodes. A significant number of patients have neck node involvement at the time of initial consultation. Lip and palate carcinoma has a lower incidence of metastases than do other intraoral lesions.

Distant Metastases

Tumors of the intraoral cavity do not show widespread metastases until late in the disease course. The main areas involved are lungs and bone. Metastasis usually occurs, with disease remaining in the head and neck region.

Treatment

The site and size of the lesion determines the treatment (surgical and radiotherapy) choice.

Special areas

Tongue

The tongue is the most common site for intraoral malignancy. The main incidence of tongue carcinoma is in the 60-year-old group. The site of most tongue cancers is the anterior two-thirds on the lateral borders or the ventral surface.

1. the lesion is often painless

2. difficulty with speech (late symptom)

3. difficulty swallowing (late symptom)

The oral tongue shows 30% lymph node metastasis on presentation.

Treatment

Surgery and irradiation are the treatment modalities.

Floor of the Mouth

Carcinoma of the floor of the mouth occurs most frequently around the age of 60, and its incidence approaches that of tongue carcinoma. The causative factors seem to be alcohol and tobacco consumption.

The site of most occurrences is anterior, although it may be in the midline. By the time the patient presents, it is not unusual to find submandibular lymph node enlargement due to metastasis. A submandibular mass causing confusion between gland enlargement due to duct obstruction or nodal enlargement due to tumor metastasis can be differentiated by fine-needle aspiration.

Treatment

Large primary tumors necessitate combined surgery and radiotherapy.

Lower Alveolus Gingiva

The lower alveolus is the third most common site of intraoral cancer. It rarely occurs in individuals below 50 years of age. Men are affected two to three times more often than women.

The presentation is one of ulceration with or without pain. Denture wearers may be unable to wear their prosthesis because of tumor bulk or pain. Frequently referral is from a dentist, as patients often consult the dentist in the first instance.

The lesion usually arises on the alveolar ridge rather than on the lingual or buccal areas. The spread is lateral rather than deep initially.

Buccal Mucosa

Squamous carcinoma of the buccal mucosa is a disease of the elderly. It accounts for only 10% of intraoral cancers. The male/female ratio is 3:128. There is a high incidence of carcinoma of the buccal mucosa in India, where it occurs at an earlier age than in the West. In the southern United States a similar picture is seen in “snuff dippers,” who develop it due to tobacco chewing. Other causative factors are trauma from the teeth, leukoplakia, alcohol, and tobacco.

The lesions begin as flat, erythematous, roughened areas, later becoming ulcerated; finally the base is indurated. Pain is not common but, when present, is a poor prognostic sign.

Palate

Squamous carcinoma of the palate is a disease of older patients. Most (80%) are men. The condition is infrequent in the Western world. The causative agents are tobacco and alcohol, and in India there is a thermal element due to reversed smoking. Often there is associated leukoplakia.

The patient notices a swelling on the palate, and there may be bleeding, occasionally pain, or problems with denture fitting. Palatal cancers may be ulcerated or exophytic; bone invasion is a late occurrence.