Chest pain is commonly caused by musculoskeletal chest wall disorders. Tietze's syndrome is a relatively rare cause of chest wall pain characterised by non-suppurative, painful swelling of the upper costal cartilages. The diagnosis should be based on these classic clinical features after excluding other potential causes of pain. A patient who was diagnosed with Tietze's syndrome but was found to have squamous cell carcinoma of the mediastinum with unknown primary site invading the sternum and anterior chest wall is presented for discussion.