Pleomorphic Adenoma

Definition

• Benign salivary gland tumour

Epidemiology

• Rare <1%
• F>M 2:1
• Age 30-60
• Most common salivary gland tumour
• Most commonly affects parotid gland

Location

• Mainly parotid 80% but can be in any other
  • Majority are superficial parotid
• Malignancy risk
  • Low at 2-5%
  • Carcinoma ex pleomorphic adenoma
  • Can be within them therefore all should be excised

Risk Factors

• Previous head and neck irradiation
• Exposure - rubber, nickel

Histology

• Proliferation of
  • Epithelial cells
  • Myoepithelial cells
  • Stromal/mesenchymal cells
• Pseudopod extensions
  • Don’t enucleate - risk of recurrence higher
• Benign
  • Circumscribed growth pattern without infiltration

Clinical

• Slow growing painless mass

Investigations

• USS - hypoechoic, lobulated, posterior acoustic enhancement
• CT - lobulated mass, homogenous, bony involvement
• MRI - soft tissue involvement
• USG - FNA or core biopsy for histology

Management

• Surgery
  • Parotid - superficial parotidectomy facial nerve preservation
    • Enucleation has high recurrence rates up to 50%
    • Total parotidectomy does NOT reduce recurrence risk
      • BUT does increase risk of nerve damage
  • Submandibular - gland excision
• Radiation
  • Indications
    • Positive margins (should really re-resect if possible)
    • Multiple recurrence
    • Inoperable primary or recurrence
• Recurrence
  • Why does it occur?
    • Pseudopod formation
    • Incomplete capsule
    • Close proximity to facial nerve and branches
• Complications of Parotidectomy
  • 5 F’s
    • Frey’s syndrome - prevention → thick flaps (SCM), post op RTX, botox
    • Formication
    • Flap necrosis
    • Fistula
    • Facial N injury

Spiel on pleomorphic adenoma

• Most common benign salivary gland tumour
• Typified by epithelial, myoepithelial and stromal proliferation
• Mainly parotid (80%)
• RFs same as other tumours - environmental exposure - rubber, nickel compounds, hairdresser. prior radiation, viral - HIV, HPV, EBV
• Important due to small risk of harboring carcinoma ex pleomorphic adenoma 5%
• Painless neck lump
• Diagnosed with CT/MRI and biopsy (FNA or core)
• Mx is with superficial parotidectomy with facial nerve preservation
• Risks of surgery include Freys, formication, fistula and facial nerve injury
• Recurrence rate low with above, higher with enucleation
• Can be given RTX for recurrence but prefer surgery if possible
• Risk increases with recurrent surgery