Warthin's tumour

Pathophysiology

• Derived from heterotopic salivary gland tissue within lymph nodes
• Composed of:
  • Bilayered oncocytic epithelium forming cystic spaces
  • Lymphoid stroma with germinal centers
• Etiology remains unclear, but smoking is a significant risk factor

Demographics

• Most common in the 6th-7th decades of life
• Male predominance (4:1 male to female ratio)
• Higher incidence in smokers
• Accounts for 5-10% of all parotid gland tumours

Diagnosis

• Clinical presentation:
  • Painless, slow-growing mass in the parotid region
  • Occasionally bilateral (5-14% of cases)
• Fine-needle aspiration cytology (FNAC):
  • Oncocytic cells and lymphocytes in a proteinaceous background
  • Diagnostic accuracy of 90%

Imaging

• Ultrasound:
  • Well-defined, hypoechoic mass with internal echogenic areas
  • Increased vascularity on colour Doppler
• CT:
  • Well-circumscribed, homogeneous mass
  • Enhancement less than normal parotid tissue
• MRI:
  • T1: Low to intermediate signal intensity
  • T2: Heterogeneous high signal intensity
  • "Cluster of grapes" appearance on T2-weighted images
• Nuclear Medicine:
  • Increased uptake on Technetium-99m pertechnetate scintigraphy

Treatment

• Surgical excision:
  • Superficial parotidectomy is the standard treatment
  • Enucleation may be considered for small, superficial tumours
• Observation:
  • May be appropriate in elderly patients or those with significant comorbidities
• Prognosis:
  • Excellent, with low recurrence rates (<2%)
  • Malignant transformation is extremely rare (<1%)
• Follow-up:
  • Regular clinical examinations and imaging studies to monitor for recurrence

Differential diagnosis