Simplified Approach to Parotid Enlargement

Diagnosis and management of a case of parotid enlargement requires systematic approach. Here, I have tried to present a simplified approach to parotid enlargement.

A) DIFFERENTIAL DIAGNOSES OF PAROTID ENLARGEMENT:

1. Infectious:

Child: Mumps, Coxsackie
Adult: S.aureus

2. Non-infectious benign:

Epithelial: Pleomorphic adenoma, Warthin tumor, Oncocytoma, Monomorphic adenoma
Non-epithelial: Lymph node, Cysts, Lipoma, Lymphoepithelial lesion, Capillary hemangioma

3. Non-infectious malignant:

Mucoepidermoid carcinoma
Adenoid cystic carcinoma
Mixed malignant tumor
Acinic cell carcinoma
Adenocarcinoma
Squamous cell carcinoma

Relevant terms:
Sialadenitis: Salivary gland inflammation
Sialolithiasis: Salivary gland/duct calculi
Sialadenosis: Non-inflammatory, symmetrical swelling usually of parotid, caused by systemic, frequently unknown cause – chronic alcoholism, vitamin deficiency, diabetes, protein deficiency, anorexia nervosa
Mumps: Acute viral sialadenitis (paramyxovirus)

B) HISTORY FOR PAROTID ENLARGEMENT:

1. Character of Parotid Mass:

Onset and duration: Rapid (inflammatory) vs slow growing (neoplastic, sialadenosis, chronic sialadenitis)
Diffuse (sialadenosis, sialadenitis) vs discrete mass (tumor)
Unilateral (acute bacterial sialadenitis, neoplasm) versus bilateral (sialadenosis, mumps – viral sialedenitis)
Painful (acute inflammatory, increases with food ingestion – sialolithiasis)

2. Contributing Factors:

Exposure to radiation or toxins (lead or mercury)
History of sarcoidosis, Sjögren’s disease, tuberculosis, gout, amyloidosis
Recent facial trauma, surgery, or dental work
Immunization history (specifically measles, mumps, rubella [MMR] vaccine)

3. Associated Symptoms and Signs: xerostomia, sialorrhea, weight loss, fever, trismus

C) PHYSICAL EXAMINATION FOR PAROTID ENLARGEMENT:

1. Differentiate if the mass is intra-parotid or extra-parotid: A parotid mass has following characteristics –

Swelling from front, below and behind the ear
Raises ear lobule
Retromandibular groove obliterated
When palpated and rolled over styloid and under mandible – not freely mobile and doesn’t move below mandible

2. Assess if the deep lobe of parotid is involved or not (involved in malignancy):

Facial nerve (CN VII) involvement
Tonsil deviation medially
Bimanually palpable

3. Fixity – to skin or masseter (malignancy)

4. Tenderness (inflammatory)

5. Expression from Stensen’s duct – Pus (parotitis) and Blood (malignancy)

6. Deep cervical lymphadenopathy (malignancy)

7. Soft/firm (benign) vs Hard/fixed (malignant)

Notes: Masseter hyperplasia can mimic parotid enlargement and is differentiated by having the patient to squeeze the jaws together which leads to activation of masseter muscle allowing for access to inspection and palpation.

D) DIAGNOSTIC STUDIES FOR PAROTID ENLARGEMENT:

1. Ultrasonography (USG):

1st choice of imaging study
can differentiate normal glandular parenchyma, inflammatory process (with or without liquefaction),cystic lesions, tumors, lymph nodes and calculi
not good for evaluating deep lobe of parotid

2. CT/MRI (MRI is superior):

When clinical examination and ultrasonography is non-yielding
Evaluating size, nerve and deep lobe involvement
Node involvement
Preoperative evaluation

3. FNA:

For discrete nodules of the parotid gland
Differentiates cysts, inflammatory processes, lymphoma, and other neoplasms
Preoperative histologic diagnosis
Predicting extent of surgery

4. Plain X-ray:

Not much helpful
Sialolithiasis: must have high calcium content and must be atleast 2-3 mm
Malignancy: bone resorption

5. Open Biopsy:

Incisional biopsy/enucleation (without identifying facial nerve):
- risks tumor seeding, recurrence, facial nerve injury, and violation of tumor margins
- contraindicated in benign tumors
Superficial/total parotidectomy (with facial nerve identification) with intraoperative frozen section: typically required

6. Technetium-99m Isotope Scan:

Rarely utilized
May differentiate a Warthin’s tumor and oncocytoma from other salivary gland neoplasms

7. Sialography:

Visualizes ductal anatomy
Indicated for ductal calculi, trauma, fistulas, Sjögren’s disease
Contraindicated in acute infections

8. Sialendoscopy:

Can demonstrate mucus plugs, calculi and stenoses
Interventional procedures like dilation or stone removal by loop or laser lithotripsy

9. Labs: may consider mumps titers, CBC, autoimmune and Sjögren’s profile (SS-A, SS-B, ANA, ESR)

E) TREATMENT FOR CAUSE OF PAROTID ENLARGEMENT:

1. Acute Sialadenitis:

Rehydration
Warm compresses
Antimicrobial therapy (may require parenteral antibiotics for severe cases)
Sialagogues (e.g. Pilocarpine)
Salivary gland massage
Oral irrigations
If no resolution after 2–3 days then consider CT or USG to evaluate for abscess (may require I&D)

2. Sialolithiasis:

Gland massage
Bimanual expression
Transoral incision
Sialodochoplasty (reconstruct duct)
Gland excision if recurrent or if stone is lodged within substance of the gland

3. Epithelial lesions:

Step 1: Superficial parotiectomy
Step 2: Frozen section
Step 3:
- Benign: Stop
- Malignant – Low/Intermediate grade: Total parotidectomy with CN VII preservation
- Malignant – High grade: Extended or Radical parotidectomy with CN VII resection and Modified radical neck dissection
- CN VII impaired and unseparable from tumor: Nerve excision followed by attempt of immediate grafting
Step 4: Postoperative radiotherapy for malignancy

Note: Warthin tumor can be treated by enucleation.
Prognosis: Low grade mucoepidermoid carcinoma > Acinic cell carcinoma > High grade mucoepidermoid carcinoma > Malignant mixed tumor > Adenoid cystic carcinoma > Squamous cell carcinoma
Indications of neck dissection: Clinically apparent cervical lymphadenopathy, tumors > 4 cm (risk of occult metastases > 20%), high grade histology (occult metastases > 40%)
Elective neck dissection for adenoid cystic carcinoma is not recommended (low risk of occult nodal metastases)
For parapharyngeal space extension: Parapharyngeal space (Infratemporal fossa) dissection

F) PRINCIPLES OF PAROTIDECTOMY

1. Superficial/Lateral Parotidectomy:

Indication: diagnostic and therapeutic excision of benign or malignant tumors that involve the superficial lobe of the parotid only
Typically preserves facial nerve
Resects majority of parotid gland lateral to facial nerve
Facial Nerve Markers
Anesthesia: General anesthesia
Incision: Preauricular and Submandibular lazy-S incision (Blair’s incision)
Ligation of greater auricular nerve is mandatory to prevent neuroma formation

2. Total Parotidectomy:

Indications: high-grade malignancy or deep lobe or facial nerve involvement
Excision of both superficial and deep lobe with preservation of facial nerve
Extended total parotidectomy: Excision of facial nerve may be indicated for malignant tumors (encasement or invasion of facial nerve)
Resection of retromandibular vein by ligation is mandatory to clear the retromandibular space
Can be done by transcervical approach

Subtotal parotidectomy: Lateral parotidectomy, somewhat medial to the facial plexus, but not necessarily including deep portion, under preservation of facial nerve.

3. Radical Parotidectomy: includes possible mandibulectomy, petrosectomy, periglandular skin, or facial nerve, indicated for aggressive malignant disease

Removal of: duct, masseter fibers, buccinator, pterygoid

Parotidectomy Complications:

Facial Nerve Paresis/Paralysis: should be repaired immediately
Hypesthesia of Greater Auricular Nerve: usually resolves within 9 months if not deliberately transected
Salivary Fistula: uncommon, usually spontaneously resolves in 2–3 weeks; Rx: probe wound to release fluid (aspiration), pressure dressing, surgical closure for prolonged drainage (may consider tympanic neurectomy)
Other Complications: hematoma, infection, flap necrosis, trismus, seroma, and recurrence
Frey’s Syndrome (Gustatory Sweating):
- Pathophysiology: injury to the auriculotemporal nerve (sympathetic fibers) results in aberrant innervation of cutaneous sweat glands (which share the same neurotransmitter) by postganglionic
  parasympathetic fibers
- may occur up to 5 years postoperatively
- less incidence with the use of “thick” skin flaps or placement of dermal grafts or allograft under skin flap
- Symptoms: sweating and reddening of skin during meals
- Investigation: Starch iodine test (Iodine + Sweat = Blue color)
- Management:
  - Medical Management: antiperspirant (aluminium chloride) and anticholinergic preparations (scopolamine, glycopyrrolate, diphemanil methylsulfate), Botox injections
  - Surgical Management: tympanic neuronectomy (Jacobson’s nerve section via tympanotomy approach, controversial) high incidence of recurrence, interpose a sheet of fascia lata or dermis
    between skin and parotid gland
  - Radiation Therapy: reserved for failed management with severe symptoms

Difference between 2 common benign tumors:

	Pleomorphic adenoma	Warthin tumor (Adenolymphoma)
Incidence	70-80 %	10%
Gender/Age	F>M; 40s	M>F; smoker; middle age/elderly
No./Site	Single/Unilateral	May be multiple/bilateral
Consistency	Nodular/Firm	Smooth, soft, cystic
Histology	Pleomorphism	2 layer epithelium and lymphoid tissue
99m Tc scan	Cold spot	Hot spot
Treatment	Superficial parotidectomy	Enucleation