Mounier-Kuhn Syndrome in an Elderly Female with Pulmonary Fibrosis

Mounier-Kuhn syndrome (MKS), or tracheobronchomegaly, is a rare clinical and radiologic condition characterized by pronounced tracheobronchial dilation and recurrent lower respiratory tract infections. Tracheobronchomegaly presents when the defect extends to the central bronchi. MKS can be diagnosed in adult women when the transverse and sagittal diameters of the trachea, right mainstem bronchus, and left mainstem bronchus exceed 21, 23, 19.8, and 17.4 mm, respectively. Its diagnosis is based on chest radiograph and chest computed tomography (CT). Patients, usually middle-aged men, may be asymptomatic or present with clinical manifestations ranging from minimal symptoms with preserved lung function to severe respiratory failure. Pulmonary function tests (PFTs) typically reveal a restrictive pattern. This report presents an elderly woman with previously diagnosed pulmonary fibrosis with symptoms of increased sputum production and haemoptysis. High-resolution chest CT showed tracheal and main stem bronchi dilatation along with bronchial diverticulosis. PFTs indicated a restrictive pattern characteristic of the underlying pulmonary fibrosis. The patient is the oldest, referred to the female gender, at presentation of MKS hitherto reported. This case highlights the need to include MKS in the differential diagnosis of recurrent lower respiratory tract infections, even in older subjects.