Hamman’s syndrome in diabetic ketoacidosis

Hamman's syndrome (spontaneous subcutaneous emphysema and pneumomediastinum) is a rare complication of diabetic ketoacidosis (DKA), with a multifactorial etiology. Awareness of this syndrome is important: it is likely underdiagnosed as the main symptom of shortness of breath is often attributed to Kussmaul's breathing and the findings on chest radiograph can be subtle and easily missed. It is also important to be aware of and consider Boerhaave's syndrome as a differential diagnosis, a more serious condition with a 40% mortality rate when diagnosis is delayed. We present a case of pneumomediastinum, pneumopericardium, epidural emphysema and subcutaneous emphysema complicating DKA in an eighteen-year-old patient. We hope that increasing awareness of Hamman's syndrome, and how to distinguish it from Boerhaave's syndrome, will lead to better recognition and management of these syndromes in patients with diabetic ketoacidosis. Learning points Hamman's syndrome (spontaneous subcutaneous emphysema and pneumomediastinum) is a rare complication of DKA.Presentation may be with chest or neck pain and shortness of breath, and signs are subcutaneous emphysema and Hamman's sign - a precordial crunching or popping sound during systole.Boerhaave's syndrome should be considered as a differential diagnosis, especially in cases with severe vomiting.The diagnosis of pneumomediastinum is made on chest radiograph, but a CT thorax with water-soluble oral contrast looking for contrast leak may be required if there is high clinical suspicion of Boerrhave's syndrome.Hamman's syndrome has an excellent prognosis, self-resolving with the correction of the ketoacidosis in all published cases in the literature.