Major Salivary Glands

• Function: Produce and secrete saliva.
• Plays a role in digestion and protection.
• Saliva composition (0.5%): Ions, Immunoglobulin A (decreases bacterial infections), Lysozyme (antibacterial enzyme), Mucin, and Lingual Lipase (from minor salivary glands).
• Saliva amylase enzyme breaks down carbohydrates.

Readings

• Robbins Chapter 16, pages 747-752
• Netter plates 18, 70, 71
• Lester, page 448-451
• Hruban Chapter 7 (page 43)

Objectives

• Identify major salivary glands and ducts anatomically.
• Differentiate salivary gland cell types and their secretions/functions.
• Recognize histological differences between major salivary glands.
• Compare and contrast common salivary gland pathologies.
• Formulate differential diagnoses based on gross pathology photos.
• Summarize clinical features of common salivary disorders.
• Formulate a gross plan for dissecting salivary gland resection.
• Create a gross description of a salivary gland resection.

Outline

• Anatomy
• Histology
• Common pathology
• How to gross
• CAP considerations
• IOC considerations

Salivary Glands

• Weight: 15–30 grams
• Location: Anterior and inferior to the ear, between skin and masseter muscle.
• Duct: Stensen's duct, empties into oral cavity opposite the second maxillary molar.
• Secretions: Serous secretions, only serous acini.
• Intraparenhymal Lymph Nodes: Present

Parotid Gland - Facial Nerve

• Facial nerve controls facial movement and expression.
• Parotid gland function can be lost or altered secondary to pathology.
• Divides into superficial and deep lobes.

Submandibular Gland

• Weight: 7–15 grams
• Location: Inferior to the body of the mandible.
• Duct: Wharton's ducts empty into the floor of the mouth on both sides of the lingual frenulum.
• Secretions: Serous and mucous (mainly serous).
• Dissections: Included in level 1B neck dissections.

Sublingual Gland

• Weight: 2-4 grams
• Location: Inferior to the tongue and deep to the oral cavity mucosa.
• Secretions: Predominantly mucous, and mixed mucinous and serous.
• Ducts: Bartholin's ducts empty into the floor of the mouth lateral to the sublingual caruncle.

Salivary Glands: Embryology/Aging

• Develop from ectodermal origin, from solid epithelial buds of oral mucosa.
• Aging: Connective tissue diminishes, myoepithelial cell function decreases, less saliva secretion, dry mouth (xerostomia) and halitosis, and altered protein content and reduced saliva production.

Salivary Glands: Histology

• Function Unit: Tubuloacinar structure, serous or mucous cells.
• Serous Acini: Secrete isotonic watery fluid, contain PAS+ intracytoplasmic granules, zymogen enzyme.
• Mucinous Acini: Produce acid and neutral sialomucins, condensed basally located nuclei.
• Myoepithelial Cells: Surround acini, mediate contractions/secretions.
• Ducts: Intercalated (lined by secretory cells, cuboidal, and ions are resorbed). Striated (ions resorbed/secreted to produce hypotonic saliva).

Minor Salivary Glands: Histology

• Found in lips, gingiva, floor of mouth, cheeks, hard palate, tongue, tonsils, oropharynx, including Von Ebner glands of the tongue (serous acini) , base/lateral border of tongue and palate (mainly mucinous); lips, cheeks, tongue apex (mixed).

Learning Check

• Location of the parotid gland?
• Submandibular gland duct name?
• Compare parotid and sublingual gland histology?
• Define a serous demilune?
• Facial nerve relationship to parotid gland?
• Salivary gland received in a Level 1B neck dissection?

Common Pathology: Major Salivary Glands

• Xerostomia, Sialolithiasis, Sialadenitis, Pleomorphic adenoma, Warthin tumor, Mucoepidermoid Carcinoma,

Xerostomia

• Dry mouth due to reduced saliva production.
• Associated with Sjogren's syndrome, head/neck cancer radiation therapy, and certain medications.
• Complications: Dry mucosa/atrophy of tongue, increased dental caries, candidiasis, dysphagia, and dyspnea.

Sialolithiasis (Stones)

• Stones obstruct salivary duct orifice, from impacts with food or local edema.
• Can cause bacterial infections (e.g., Staphylococcus aureus).
• The result are dilated ducts, pain, swelling of the gland, necrosis, edema of the salivary gland.
• Chronic inflammation can result in Sialadenitis.

Sialadenitis (Inflammation)

• Causes: Trauma, viral (e.g., mumps), bacterial, autoimmune conditions (e.g., Sjogren's syndrome).
• Most common viral cause: mumps.
• Prevalent form is Mucocele (CPT 88304). Swelling of lower lip, often a blue hue caused by damage or blockage in minor salivary gland ducts.

Salivary Gland Neoplasms

• 65–85% arise in the parotid gland; 10% are in the submandibular gland.
• Majority of sublingual tumors and 50% of minor salivary gland tumors are malignant.
• Majority of parotid tumors are benign; 40% of submandibular tumors are malignant.
• Most common neoplasm: Pleomorphic adenoma.

Pleomorphic Adenoma

• Benign mixture of ductal, myoepithelial, and mesenchymal cells.
• Can arise from radiation exposure.
• Make up 60% of parotid tumors.
• Recurrence possible if unencapsulated.
• Morphology: Round, well demarcated, rarely exceeds 6 cm. Cut surface: gray-white, sometimes with myxoid/translucent chondroid stroma areas.

Warthin Tumor (Papillary Cystadenoma Lymphomatosum)

• 2nd most common salivary gland tumor (mostly parotid gland inferior lobe)
• Benign
• 8x increased risk in smokers
• Occurs more frequently in men.
• Gross Features: Circumscribed, orange/tan, often cystic; thick brown/black fluid within cyst; cyst lined with papillary nodules; can be multifocal and 10% bilateral.

Mucoepidermoid Carcinoma

• Most common primary malignant salivary gland neoplasm (60–70% in parotid gland).
• Accounts for a large fraction of minor salivary gland tumors
• Can be low-grade (well-circumscribed, cystic with mucin) or high-grade (infiltrative and solid).

Minor Salivary Gland Biopsy of the Lip

• Sjogren Syndrome patients: Labial biopsy of normal appearing mucosa for diagnosis.
• Recommended biopsy number: > 0.2 cm, at least 4; < 0.2 cm, minimum of the size; 3 levels are recommended.

Salivary Gland Resection

• Orientation (if present), 3D measurements.
• Describe outer surface (large nerves, etc.).
• Ink the outer surface.
• Serial sectioning perpendicular to long axis (2–3 mm).
• Describe the lesion.
• Describe remaining uninvolved cut surface.
• Take sections

Example Dictation

• Case example of a parotid gland with a 10g, 6 x 5 x 3 cm lesion.
• Adipose tissue surrounding, 0.1 to 0.5 cm in thickness.
• 0.5 cm long, 0.2 cm diameter nerve.
• Ink lesion/soft tissue margin.
• No lymph nodes are grossly identified.
• Sections A1-2: Full face of lesion (bisected); A3: lesion to closest soft tissue resection margin; A4: lesion to large nerve; A5: uninvolved gland.

CAP Protocol: Major Salivary Glands

• Procedure: Parotidectomy, submandibular, sublingual resection.
• Focality, Site, Laterality.
• Size (3D).
• Macroscopic extent (pT3, pT4a, pT4b).
• Margin status.
• Lymph nodes (size of nodal deposit if positive, ENE)

Tumor Classification (T)

• TX - Primary tumor cannot be assessed.
• T0 - No evidence of primary tumor.
• Tis - Carcinoma in situ.
• T1 - Tumor 2cm or smaller
• T2, T3, T4 - Tumors greater in size or exceeding surrounding tissues (T4a and T4b are further classified by the specific tissues invaded).
• Notes: This is not an exhaustive list of all possible tumor classifications

Key Points from CAP Protocol

• Adenoid cystic carcinoma is not low-grade.
• Perineural invasion is a poor prognosis indicator for head and neck cancers.
• Facial nerve involvement necessitates neck dissection, postoperative radiation.
• Primary salivary gland carcinoma involving the facial nerve is associated with recurrence and reduced survival.
• Complete surgical excision with free surgical margin is crucial.
• Lymph node metastasis cross-sectional diameter at time of gross is important.
• Selective/Radical/Modified neck dissection LN counts are important staging factors.
• Extraparenchymal extension implies invasion.
• Microscopic evidence alone does not suffice.

IOC Considerations

• Salivary gland tumors may be received for IOC (intraoperative consultation) if additional histological assessment is required during surgery.

Additional Note

• There are diagrams and graphs that are not included in this summary, please note that these may be important components of the study material that are omitted or unavailable in a text-based format

Test your knowledge on salivary glands, their functions, and associated pathologies. This quiz covers key features, therapy modes, and histological aspects relevant to salivary gland health. Prepare to answer questions about the anatomy and clinical considerations of salivary glands.