80% PAROTID GLAND
80% PLEOMORPHIC ADENOMAS
Classification
Benign:
- Pleomorphic adenoma
- Mixed salivary tumour
- Adenolymphoma
Malignant:
- Primary:
- Carcinoma
- Secondary:
- Direct invasion from skin or from secondarily involved lymph nodes
Pleomorphic adenoma
- 90% occur in parotid
- Occasionally found in submandibular, sublingual or accessory salivary glands
- 90% present <50 yrs
Pathology
- Macroscopic appearance
- Lobulated
- Lies with a false capsule of salivary tissue
- Cut surface – glistening and transluscent
- Crumbly consistency
- Microscopic appearance
- Vary across a spectrum from typical adenoma to frank carcinoma
- Majority show glandular acini within blue-staining stroma
- Gives appearance of cartilage but is in fact mucus
- Appearance of epithelial cells and ‘cartilage’ gave rise to early concept of ‘mixed tumour’
Surgical considerations
- Treated by enucleation
- At least 25% recur:
- Capsule surrounding tumour is false, which itself is incomplete and may contain cancer cells
- Serial sections show tumour often has ‘amoeboid’ processes – may be left behind
- Implantation of tumour cells may occur into the wound
- Slow growing, but cannot be considered benign:
- Lack of encapsulation
- Occasional wide infiltration into surrounding tissues
- Tendency to recur
- Less differentiated tumours (difficult to distinguish from frank carcinoma) may metastasise to regional lymph nodes and distantly via blood stream
Clinical features
- Patient presents with slow-growing swelling anywhere within parotid gland
- Usually lower pole
- Region of the angle of the jaw
- Well-defined lump
- Firm or hard (sometimes cystic)
- Usually superficial part of gland
- Occasionally can be in deep prolongation – may project into pharynx
- Facial nerve never involved, except in frankly malignant tumours
- Integrity should be confirmed
Treatment
- Wide excision of tumour and surrounding parotid tissue
- Careful preservation of fibres of the facial nerve
- Superficial parotidectomy
- Where tumour involves other salivary gland, complete excision of gland performed
- Careful preservation of fibres of the facial nerve
Prognosis
- Excellent provided tumour is completely excised
- Inadequate surgery leads to high rate of recurrences
Adenolymphoma (Warthin’s Tumour)
- Accounts for approx 10% parotid tumours
- Very rare elsewhere
- Usually men >50yrs
- Occasionally bilateral
- Macroscopically
- Soft and cystic
- Microscopically
- Columnar cells forming papillary fringes, which project into cystic spaces and are supported by a lymphoid stroma
- Probably arise from salivary duct epithelium
- Lymphoid tissue originating from lymphoid aggregates present in normal parotid tissue
- Presence of lymphoid tissue may lead to confusion with lymphoproliferative disorders
- Prognosis after excision – excellent
Carcinoma
Clinical features
- Usually affects parotid
- Equal sexy distribution
- Patients usually >50yrs
- Tumour hard and infiltrating
- Clinical diagnosis based on:
- Rapid growth
- Pain
- Involvement of facial nerve
- Regional lymph nodes
- Eventually surrounding tissues infiltrated
- Overlying skin becomes ulcerated
- Microscopically
- Mostly adenocarcinomas
- Rapidly progressive with high incidence of regional lymph node mets
Treatment
- Radical parotidectomy with sacrifice of facial nerve
- Combined if necessary with block dissection of regional lymph nodes
- Followed by radiotherapy
- If arises from other salivary glands; wide excision with block dissection of regional lymph nodes if necessary
- Prognosis not good
- Especially if arises from submandibular gland
Adverse effects
- Frey's Syndrome:
- Symptoms
- Redness and sweating on cheek area adjacent to ear
- Appearance:
- Any action that may produce strong salivation
- Sweating in the region after eating a lemon wedge may be diagnostic
- Treatments
- Injection of botulinum toxin type A
- Surgical transaction of the nerve fibres (temporary)
- Application of ointment containing anticholinergic drug
- E.g. scopolamine