What is the most useful investigation for a 16-year-old boy with a painless neck swelling and enlarged lymph nodes?

In the case of a 16-year-old boy presenting with a painless neck swelling and enlarged lymph nodes, fine-needle aspiration of the cervical lymph node is the most useful initial investigation. This minimally invasive procedure allows for the collection of cells from the lymph node, which can be sent for cytological analysis. It provides rapid and valuable information regarding the nature of the swelling, helping to distinguish between benign processes, such as infections or reactive lymphadenopathy, and malignancies, such as lymphoma.

The advantage of fine-needle aspiration lies in its ability to yield a quick diagnosis without the need for more invasive surgical procedures. It can often be performed in an outpatient setting, and because it requires only local anesthesia, it carries fewer risks compared to other investigative methods. The results can guide further management and any necessary follow-up investigations.

While a CT scan of the head and neck can provide useful imaging to assess the extent of the lymphadenopathy and may help in planning further treatment, it does not provide histological information that is crucial in guiding the management of the swelling. Excision biopsy, while definitive for diagnosis, is usually reserved for cases where fine-needle aspiration is inconclusive or if malignancy is highly suspected based on clinical and cytological findings. Bone