We read with great interest the well-written manuscript by Habesoglu et al. regarding the clinical, radiologic, and functional evaluation of patients with bronchiectasis. The authors point out the different etiologies of the diseases that result in bronchiectasis, reporting that in their series, most commonly bronchiectasis was post-infectious due to childhood infections, tuberculosis, and severe pneumonia. They also emphasize the role of high-resolution computed tomography (HRCT) as the gold standard diagnostic method in bronchiectasis.
We recently observed a case of a 27-year-old man who was referred to our department for investigation of recurrent respiratory infections. The patient reported a history of progressive dyspnea for three years, which had recently worsened with moderate and high physical activity. During the last two years, he had experienced six infectious exacerbations with increased expectoration, which became purulent. Physical examination was unremarkable, except for scattered bilateral crackles. Chest radiography and HRCT revealed widening of the trachea and main stem bronchi, and extensive bronchiectasis [Figure 1]. This tomographical pattern is consistent with Mounier-Kuhn syndrome. Pulmonary function tests showed a forced vital capacity (FVC) of 3.08 l (64% of predicted), a forced expiratory volume in one second (FEV1) of 2.14 l (53% of predicted), and a FEV1/FVC of 0.60 (71% of predicted). The patient showed no response to the bronchodilator. Fiberoptic bronchoscopy revealed markedly enlarged airways. Currently, the patient is undergoing outpatient clinical treatment and physiotherapy.
Mounier-Kuhn syndrome or tracheobronchomegaly is a rare condition characterized by marked dilatation of the trachea and major bronchi.[2–4] The etiology is unknown, but a decrease in elastic and muscle tissue of the trachea and main bronchi has been reported. As a result, some patients may develop mucosal herniations through the tracheal rings, leading to tracheal diverticulosis. The grossly enlarged but weakened airways and inefficient cough mechanisms block mucociliary clearance, leading to mucus retention with resultant recurrent lower respiratory tract infections, bronchiectasis, and fibrosis.[2,4]
The clinical manifestations of Mounier-Kuhn syndrome are nonspecific. Many patients have few or no symptoms, and no apparent disease progression.[2,3] However, some may have symptoms of bronchiectasis and chronic recurrent pulmonary infections, such as productive cough, copious purulent sputum, occasional hemoptysis, and progressive dyspnea. In some patients, this leads to respiratory failure as the lungs become progressively more damaged. Once established, infections are likely to accelerate the damage to the tracheobronchial tree.[2,3] Other possible complications include spontaneous pneumothorax, massive hemoptysis, and finger clubbing.[3,4]
In conclusion, Mounier-Kuhn syndrome should be considered in patients who presented with bronchiectasis associated with abnormal dilation of trachea and major bronchi on CT scans. HRCT not only allows the identification of bronchiectasis, determining the extent and type of the disease, but also allows in some cases the establishment of the etiology of bronchiectasis.