Questions and Answers
What is the most common tumor of salivary glands?
What is the characteristic of the capsule of pleomorphic adenoma?
At what age does pleomorphic adenoma typically occur?
What is the distribution of pleomorphic adenoma between males and females?
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What is Warthin's tumor also known as?
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Where is Warthin's tumor usually found?
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What is the growth rate of pleomorphic adenoma?
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What is the risk of pleomorphic adenoma turning into carcinoma?
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What is the presentation of carcinoma ex pleomorphic adenoma?
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What is the impact of preserving the facial nerve during parotid surgery?
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What is the most useful method for assessment of salivary neoplasms?
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What is a contraindication for salivary gland tumors?
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What is the commonest cause of submandibular sialadenectomy?
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What is a unique feature of adenolymphoma and oncocytoma?
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During which procedure can 3 nerves be injured?
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What is the goal of treatment for low-grade mucoepidermoid carcinoma?
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How many minor salivary glands are found in the oral cavity?
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What is the location of the parotid gland?
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What is the diameter of the parotid duct?
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How many major salivary glands are there?
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During which weeks of gestation do the salivary glands develop?
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What is the name of the duct that arises from the anterior border of the parotid?
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What is unique about the parotid gland among the major salivary glands?
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What is the location of the parotid fascia?
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What is a characteristic of a parotid salivary fistula?
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What is the primary goal of using atrropine derivatives in parotid gland fistula treatment?
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What is a possible complication of avulsion of the auriculotemporal nerve in parotid gland fistula treatment?
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What is the percentage of salivary neoplasms that are benign?
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What is the percentage of parotid neoplasms that are malignant?
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What is the percentage of sublingual and minor salivary glands neoplasms that are malignant?
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What is the percentage of salivary neoplasms that arise in the parotid gland?
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What is the primary location of parotid gland fistula in relation to the gland?
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Where is the parotid duct located in relation to the arch?
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What is the direction of the parotid duct after it runs superficial to the masseter muscle?
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What nerve runs with the parotid duct?
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What is the surface anatomy of the parotid duct opening?
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What structure is the deepest in the parotid gland?
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What divides the parotid gland into major superficial and small deep lobes?
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What nerve supplies secretomotor fibers to the parotid gland?
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What structures are revealed after complete removal of the parotid gland?
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Study Notes
Salivary Glands
- There are two main types of salivary glands: major and minor.
- Major salivary glands: parotid, submandibular, and sublingual.
- Minor salivary glands: multiple scattered glands (around 600-1000) located in the submucosa of the oral cavity, hard and soft palate, nasal cavity, nasal and paranasal sinuses, pharynx, and larynx.
Embryology
- Salivary glands develop between the 6th and 8th weeks of gestation.
- The parotid gland is the first to develop and grows in a posterior direction, surrounding the facial nerve.
- The parotid gland is the last to become encapsulated, after the lymphatics develop, resulting in entrapment of lymphatics in the parenchyma of the gland.
Anatomy of Parotid Gland
- Location: in front of and below the lower half of the ear, wrapped around the vertical ramus of the mandible, and projecting forward on the surface of the masseter.
- The gland can only be felt in pathological conditions.
- The parotid duct (Stensen's duct) arises from the anterior border of the parotid gland and parallels the zygomatic arch.
- The duct measures 5 cm in length and 5 mm in diameter, and opens into the oral cavity at the level of the second maxillary molar teeth.
Surface Anatomy of Parotid Duct Opening
- Located at the level of the second maxillary molar teeth, where the duct opens into the oral cavity.
Structures Within the Parotid Gland
- External carotid artery and its two terminal branches (maxillary and superficial temporal arteries).
- Retromandibular (posterior facial) vein.
- The facial nerve and its branches.
- Parotid lymph nodes are embedded in the gland beneath the parotid fascia.
Relations of Parotid Gland
- Nerve supply: secretomotor fibers are originally supplied by the glossopharyngeal nerve and reach the gland through the auriculotemporal branch of the trigeminal nerve.
Parotid Salivary Fistula
- May be connected to the duct or gland.
- Fistula related to the gland is usually related to the lower pole of the parotid.
- Salivary discharge is increased by meals and sucking of a lemon.
Treatment of Parotid Salivary Fistula
- Treatment options include:
- Atropine derivatives to decrease salivation.
- Irradiation needle inside the fistula to cause fibrosis.
- Avulsion of the auriculotemporal nerve to cause atrophy.
- Excision of the fistula with the lower part of the gland and closure of the fascia.
- Conservative superficial parotidectomy may be done.
Types and Treatment of Parotid Duct Fistula
- Treatment options include:
- Excision and end-to-end anastomosis.
- Slitting the opening of the duct proximal to the site of the fistula.
- Reimplantation of the fistulous opening to the inner side of the cheek.
- If the fistula affects the distal 2 cm of the duct, a rectangular pedicle flap of mucosa from the inner aspect of the cheek is used.
- If the above options fail, superficial parotidectomy may be done.
Salivary Neoplasms
- Incidence: 1.2% of all neoplasms and 5% of head and neck tumors.
- The majority of salivary neoplasms are benign and most commonly arise in the parotid gland.
- The incidence of malignancy varies inversely with the size of the gland.
Classification of Salivary Neoplasms
- Benign:
- Pleomorphic adenoma (mixed salivary tumor).
- Monomorphic adenoma.
- Warthin's tumor (adenolymphoma).
- Oncocytoma (oxyphil adenoma).
- Malignant:
- Mucoepidermoid carcinoma.
- Adenoid cystic carcinoma (cylindroma).
- Acinic cell carcinoma.
- Adenocarcinoma.
- Carcinoma ex pleomorphic adenoma.
- Epidermoid carcinoma (squamous cell carcinoma).
- Lymphoma.
Pathology of Benign Salivary Neoplasms
- Pleomorphic adenoma:
- The commonest tumor of salivary glands.
- Represent 75% of parotid and 50% of submandibular gland neoplasms.
- Distribution is equal between males and females.
- It occurs in the fourth decade of life, but any age and sex may be affected.
- Pathology: epithelial, myoepithelial, and stromal components with wide variations in cellular and architectural morphology.
- The tumor is characterized by an incomplete capsule that allows extension of the neoplastic epithelium into the surrounding tissues.
- Warthin's tumor:
- Is usually found in the lower part of the parotid gland.
- The classical signs of facial palsy or lymph node enlargement occur with advanced disease.
Notes
- Salivary neoplasms:
- Carcinoma ex pleomorphic adenoma presents as a painless swelling that has been stationary for years and is now getting bigger.
- Pleomorphic adenoma of the parotid raises the lobule of the ear and does not affect the facial nerve.
- Open surgical biopsy of the major salivary glands is contraindicated; FNAC is safer.
- For tumors of the minor salivary glands of the mouth cavity, excision biopsy is feasible.
- CT and MRI are the most useful methods for assessment.
- Even if the facial nerve is preserved in parotid surgery, nerve weakness commonly develops because of neurapraxia that recovers spontaneously a few months after the operation.
- The majority of tumors that arise in the parotid gland are superficial to the facial nerve.
- During submandibular sialadenectomy, 3 nerves can be injured (mandibular division of facial N, lingual, and hypoglossal nerves).
- The commonest cause of submandibular sialadenectomy is a stone in it.
- For low-grade mucoepidermoid carcinoma, an attempt to preserve the facial nerve is warranted.
- For tumors that are clinically malignant, treatment is modified according to the aggressiveness of the tumor.
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