Dermatomyositis masquerading as angioedema: a crucial differential not to overlook

Dermatomyositis is a rare autoimmune disease that typically affects the skin, muscle and respiratory system. Patients with dermatomyositis usually require prompt treatment with intense immunosuppression to reduce disease progression and multiorgan damage. A previously well male in his 40s initially presented to an emergency department with severe neck swelling. He was reviewed initially by ear, nose and throat surgeons for a probable deep neck space infection. Having been cleared of this as a cause, he was referred to clinical immunology for investigation and treatment of suspected idiopathic angioedema. A creatine kinase level was promptly requested due to the atypical nature of neck oedema that was inconsistent with angioedema, along with the presence of skin and nail changes. The patient was given a provisional diagnosis of dermatomyositis and subsequently was shown to have a positive small ubiquitin-like modifier-1 activating enzyme (SAE1) autoantibody and typical muscle biopsy. This case highlights non-histamine and non-bradykinin-mediated neck swelling as an unusual presentation of dermatomyositis that manifested with dysphagia and significant muscle involvement requiring prompt treatment.