Which initial investigations should be performed for a patient presenting with unexplained lymphadenopathy?

For a patient presenting with unexplained lymphadenopathy, the initial investigations should include an urgent full blood count (FBC) within 48 hours to assess for possible leukaemia, especially if the lymphadenopathy is generalized.

Consider arranging an urgent chest X-ray within 2 weeks for patients aged 40 years and over with supraclavicular or persistent cervical lymphadenopathy to exclude lung cancer, tuberculosis, or sarcoidosis.

In adults aged 25 years or more, and in children and young people up to 24 years, consider referral via a 2-week suspected cancer pathway to exclude lymphoma, particularly if lymphadenopathy is unexplained or accompanied by splenomegaly.

Additional investigations may be guided by clinical features suggestive of specific infections (e.g., Epstein-Barr virus, cytomegalovirus, HIV) or malignancy (e.g., persistent lymphadenopathy beyond 2–4 weeks, systemic symptoms such as night sweats, weight loss, pruritus).