What investigations should be considered for a patient with a neck lump and associated systemic symptoms such as weight loss or night sweats?

A patient presenting with a neck lump and associated systemic symptoms such as weight loss or night sweats should be urgently investigated for possible lymphoma or other malignancies. Initial investigations should include a very urgent full blood count (FBC) within 48 hours to assess for haematological malignancies such as leukaemia. Consider a suspected cancer pathway referral for specialist assessment within 48 hours if there is unexplained lymphadenopathy with systemic symptoms like night sweats, weight loss, fever, or pruritus, as these may indicate Hodgkin's or non-Hodgkin's lymphoma.

Additional investigations may include imaging such as a chest X-ray to exclude thoracic involvement, especially if respiratory symptoms or risk factors are present. The referral and investigation urgency is heightened in adults and children/young people with these symptoms, with pathways adapted by age and local arrangements.