What is the likely diagnosis for a child with a tender neck mass and symptoms of an upper respiratory infection?

In the context of a child presenting with a tender neck mass accompanied by symptoms of an upper respiratory infection, the likely diagnosis is lymphadenopathy. Lymphadenopathy refers to the enlargement and tenderness of lymph nodes, which commonly occurs in response to infections, including respiratory tract infections.

When children develop upper respiratory infections, the surrounding lymph nodes, particularly those in the cervical region, often react by becoming swollen and tender as they work to filter pathogens and mount an immune response. These lymph nodes can become palpable and may cause discomfort for the child, which aligns with the presence of a tender neck mass.

Other potential diagnoses such as a thyroglossal cyst or branchial cleft cyst typically present as non-tender masses and are generally not associated with acute infectious symptoms; they are more chronic and usually do not exhibit tenderness unless they become infected. An abscess, while it could cause a tender mass, would typically be associated with a more localized infection, such as a bacterial skin infection or an infected lymph node, and usually presents with more pronounced systemic signs of infection (fever, redness, etc.).

Thus, given the context of upper respiratory symptoms in conjunction with a tender neck mass, lymphadenopathy is the most appropriate diagnosis, reflecting the body's