Breathlessness and neck swelling after a rugby game

A 16 year old boy presented to the emergency department with breathlessness and painful neck swelling after playing in a game of rugby. He had not sustained any trauma to the neck or chest. He had a history of asthma and had recently had an upper respiratory tract infection. His breathlessness was not helped by his salbutamol and he described the neck swelling and breathlessness progressively worsening since the match. What abnormalities are identified in the radiograph (fig 1⇓) and what do they signify …