B71-26 Mounier-Kuhn Syndrome Presenting as Hemoptysis: A Case Report

Abstract Introduction Tracheobronchomegaly, also known as Mounier-Kuhn Syndrome, is a rare disorder characterized by marked dilation of the trachea and bronchi resulting from atrophy of the elastic fibers and muscularis propria in the airway wall. Patients typically exhibit nonspecific chronic respiratory symptoms, which often contribute to a delay in diagnosis. In this report, we describe a case presenting with hemoptysis and recurrent lower respiratory tract infections. The diagnosis of Mounier-Kuhn syndrome was established based on findings from high-resolution computed tomography (HRCT). Case presentation A 74-year-old male, a retired worker, was transferred to our hospital following episodes of hemoptysis and recurrent lower respiratory tract infections. He reported a previous smoking history of 5 years, with a consumption of approximately 10 cigarettes per day, but currently denies tobacco use. The laboratory data were as follows: white blood cell count 13.3 × 109/l, neutrophils 11.34 × 109/l, C-reactive protein 176.4 mg/L, and positive procalcitonin (PCT, 1.53 ng/mL). High-resolution computed tomography (HRCT) was performed, and coronal reconstruction demonstrated marked dilation of the trachea and main bronchi, with diameters measuring 30.2 mm in the trachea, 26.3 mm in the right main bronchus, and 23.7 mm in the left main bronchus (Figure 1 A). On the sagittal view, the tracheal diameter reached 33.32 mm (Figure 1 B). Three-dimensional reconstruction further revealed extensive tracheobronchial dilatation accompanied by multiple diverticula (indicated by arrows, Figure 1 C). Subsequent fibrobronchoscopy confirmed the presence of tracheomalacia with dynamic partial collapse during expiration (Figure 1D.E.F). Finally, he was diagnosed as Mounier-Kuhn syndrome. Discussion Tracheobronchomegaly (Mounier-Kuhn Syndrome) is a rare disorder that has been underdiagnosed since its first description in 1932. Computed tomography (CT) serves as the cornerstone for establishing the diagnosis and guiding comprehensive evaluation. The characteristic hallmarks—marked airway dilation, tracheobronchial diverticulosis, and related complications—should be recognized to facilitate accurate diagnosis, inform appropriate management, and avoid unnecessary interventions. In the management of Mounier-Kuhn syndrome, a symptom-driven approach is recommended. No specific treatment is indicated for asymptomatic patients, whereas tobacco cessation constitutes a cornerstone of care. For symptomatic individuals, the mainstay of management includes routine respiratory physiotherapy and the use of antibiotics to manage acute infectious exacerbations. This report aims to enhance awareness of the common complications and associated pulmonary conditions in these patients. This abstract is funded by: None