Warthin's tumours are the second most common benign parotid tumours in the UK. The World Health Organization states that 5–14 per cent of patients have bilateral Warthin's tumours. This study aimed to: assess the presence of contralateral Warthin's tumours in patients who underwent surgery over the past 16 years at a head and neck unit in England, and perform the first systematic literature review on bilateral Warthin's tumours.

A retrospective analysis was conducted on patients diagnosed with Warthin's tumour based on histology between 2005 and 2020. Additionally, a systematic review (International Prospective Register of Systematic Reviews (‘PROSPERO’) registration number: CRD42022326846) was performed using PubMed and the Cochrane Library.

Among 290 patients diagnosed with Warthin's tumours based on histology following surgery, 24.5 per cent had bilateral Warthin's tumours. The systematic review identified 157 papers, with 14 meeting the inclusion criteria.

This study revealed that 24.5 per cent of patients had bilateral Warthin's tumours, deviating from the suggested range. These findings are of interest to surgeons discussing the disease with patients.

Warthin's tumours can show features of pseudo-neoplasia. They do not usually cause problems for diagnosis and management when present within the parotid gland. However, extraparotid Warthin's tumours that are associated with pseudo-neoplasia upon cytological analysis can mimic metastatic malignant disease. The case of a patient presenting with multifocal extraparotid Warthin's tumours is described.

A 57-year-old male smoker presented with rapidly growing upper neck lumps. Fine needle aspiration cytology, magnetic resonance imaging and positron emission tomography findings were compatible with metastatic squamous cell carcinoma secondary to either an unknown primary upper aerodigestive or a parotid malignancy. The patient subsequently underwent total conservative parotidectomy and modified radical neck dissection. Final histology findings revealed multifocal benign Warthin's tumours with four extraparotid components.

Warthin's tumours may present outside the parotid gland, present with multifocal lesions and mimic metastatic disease. Frozen section examination prior to radical resection should be considered to guide management.