Severe laryngeal oedema unexpectedly observed during bronchoscopy in a patient with anti-MDA5-positive dermatomyositis

A woman in her 70s presented to the emergency department with generalised fatigue. She presented with characteristic skin findings without muscle weakness, which suggested new-onset amyopathic dermatomyositis. She had mild hypoxia without signs of upper airway obstruction. Chest CT revealed peripheral ground-glass opacities, and connective tissue disease-associated ILD was suspected. During the bronchoscopy examination, we unexpectedly observed severe laryngeal oedema, which necessitated urgent tracheal intubation. We thought it had developed suddenly, with no symptoms until just before. Following hospital admission, she was confirmed to be positive for anti-MDA5 antibody. Her ILD progressed despite appropriate treatment, and she ultimately died. An autopsy revealed localised laryngeal oedema with histiocyte infiltration, which suggested laryngeal oedema related to anti-MDA5-positive dermatomyositis. This case report indicates that laryngeal oedema may occur in these patients and rapidly progress to a severe condition. Therefore, it may be necessary to evaluate the risk of airway compromise.