Spontaneous pneumomediastinum with extensive subcutaneous emphysema secondary to upper respiratory tract infection.

Spontaneous pneumomediastinum (SPM) is a rare condition in which air accumulates within the mediastinum without preceding trauma or medical procedures. It typically affects young adults and may present with acute chest pain, dyspnoea or subcutaneous emphysema. The Macklin effect-alveolar rupture with air tracking along bronchovascular sheaths-explains its pathophysiology, and Hamman's sign may be detected on auscultation.We present a female in her mid-20s who developed shortness of breath and neck swelling after a 5 day sore throat without cough. Examination revealed subcutaneous crepitus, and CT confirmed pneumomediastinum with extensive subcutaneous emphysema. She was managed conservatively with high-flow oxygen, analgesia and antibiotics, improving markedly within 24 hours. No surgical intervention was required, and follow-up imaging showed complete resolution.SPM should be suspected in patients with respiratory symptoms and subcutaneous emphysema, even without trauma or typical risk factors. Prompt diagnosis and supportive management usually result in excellent outcomes.