31st May 2023

An 18-year-old female presents to her GP with a history of discomfort in her neck associated with drinking alcohol

An 18-year-old female presents to her GP with a history of discomfort in her neck associated with drinking alcohol. She is otherwise asymptomatic and has no past medical history. On examination, there is a 3cm firm mass palpable in her right supraclavicular region. A full blood count is unremarkable.

Which investigation should be performed to confirm the diagnosis?