Warthin Tumor

Warthin tumour (papillary cystadenoma lymphomatosum, adenolymphoma) is the second commonest benign parotid neoplasm, forming 5 to 15 percent of parotid tumours. It is almost exclusive to the parotid gland, particularly the superficial lobe and the lower pole (tail), and develops within intraparotid lymph nodes through epithelial inclusion. Bilateral or multifocal disease occurs in about 10 to 15 percent.

Smoking is the strongest risk factor, with an 8-fold increase in smokers and a dose response relationship; radiation exposure and chronic inflammation are other factors. The male to female ratio has narrowed to 1 to 1 as female smoking increased, and peak age is 50 to 70 years. Histology shows a bilayered oncocytic epithelium lining cystic spaces with papillary projections, within a dense lymphoid stroma with germinal centres.

Growth is slow, malignant transformation is very rare (under 0.3 percent), and recurrence after complete excision is under 2 percent. Pathological uptake of technetium-99m pertechnetate is a characteristic feature because oncocytes concentrate the tracer.

• Painless, soft, cystic or doughy, well circumscribed, mobile swelling in the tail of the parotid, below the ear and behind the angle of the mandible.
• Slow growth over months to years; fluctuating size, with occasional rapid enlargement after infection or infarction.
• Multiple or bilateral lumps in 10 to 15 percent.
• Facial nerve function is normal.
• Rarely pain, tenderness, or cutaneous inflammation (infarcted tumour).
• Red flags: facial weakness, fixation, rapid enlargement without infection, cervical nodes, and ulceration (consider malignancy).

• Clinical assessment of lesion consistency, mobility, and facial nerve; document smoking history.
• Ultrasound: well defined, oval, hypoechoic to cystic mass with internal septation and posterior acoustic enhancement; multiple lesions suggest this diagnosis.
• FNAC (ultrasound guided): oncocytic epithelial cells in sheets, lymphocytes and a granular, proteinaceous cystic background; false negatives possible.
• Technetium-99m pertechnetate scintigraphy shows increased uptake (a "hot" nodule), which distinguishes Warthin tumour and oncocytoma from most other tumours; useful in difficult cases.
• MRI: T2 hyperintense mass with intermediate signal and dynamic contrast washout pattern, low apparent diffusion coefficient; CT if needed.
• Core needle biopsy where cytology is equivocal.
• Exclude pleomorphic adenoma, lymph node disease (lymphoma, tuberculosis, HIV lymphoepithelial cyst), oncocytoma, mucoepidermoid carcinoma, acinic cell carcinoma, and metastasis.

• Observation with ultrasound surveillance is acceptable for asymptomatic, small (under 3 cm), elderly patients or those with comorbidities, once the diagnosis is confirmed by FNAC or core biopsy and scintigraphy: ultrasound at 6 months and then yearly; excise if growth, symptoms or doubt occur. Growth is typically under 1 cm in 5 years.
• Surgery for symptomatic, growing, cosmetically troublesome lesions, or when the diagnosis is uncertain: extracapsular dissection for small superficial tumours (lower rate of facial nerve injury, 0.5 percent permanent) or partial superficial parotidectomy with facial nerve identification; total parotidectomy is not required.
• Perioperative: cefazolin 1 g intravenously at induction, single dose; suction drain for 24 to 48 hours; paracetamol 1 g every 6 hours and ibuprofen 400 mg every 8 hours as analgesia.
• Complications: temporary facial weakness (5 to 15 percent), Frey syndrome (up to 10 to 20 percent, treated with botulinum toxin A 2 to 3 units per cm2 intradermal), salivary fistula or sialocele (aspirate and pressure dressing; botulinum toxin 25 units for persistent cases), numbness of the ear lobe, and haematoma.
• Smoking cessation: nicotine replacement (patch 21 mg per 24 hours for 6 weeks, 14 mg for 2 weeks, 7 mg for 2 weeks) or varenicline (0.5 mg daily for 3 days, 0.5 mg twice daily for 4 days, then 1 mg twice daily for 12 weeks); reduces new lesions.
• Bilateral or multifocal lesions: stage the excision, treating the symptomatic or larger lesion first.
• Follow up: clinical review at 6 weeks and 12 months; yearly for 3 years after excision for new ipsilateral or contralateral tumours (metachronous lesions in about 10 percent).
• Counselling: benign nature, very low recurrence, and the relationship with tobacco use.