SESSION TYPE: Bronchology Student/Resident Case Report Posters
PRESENTED ON: Tuesday, October 23, 2012 at 01:30 PM - 02:30 PM
INTRODUCTION: Mounier-Kuhn syndrome, also known as congenital tracheobronchomegaly, is a clinical entity characterized by marked dilation of the trachea and main bronchi with recurrent respiratory tract infections, bronchiectasis and tracheal diverticulosis(1). While tracheomegaly may be seen in a variety of congenital and acquired disorders, tracheobronchomegaly is most commonly congenital in origin. Histologic examination of the trachea shows a deficiency or absence of smooth muscle and elastic fibers(2).
CASE PRESENTATION: A 41-year-old male with a ten-year history of recurrent bronchitis presented to clinic for a second opinion. He was previously diagnosed with COPD despite being a lifelong nonsmoker with an FEV1/FVC ratio of 77% and an FEV1 of 95% predicted. He had been treated with inhaled steroids and albuterol without improvement; he also received frequent courses of antibiotics. Between episodes, he reported an intermittent cough productive of clear sputum, but was otherwise asymptomatic. His lung exam was unremarkable. A CT scan of his chest showed an enlarged, dysmorphic trachea, transverse and sagittal tracheal diameters of 34.2mm and 27.5mm respectively, bilateral diffuse areas of cortical bronchiectasis and bibasilar linear parenchymal scarring. Main stem bronchi diameters were not measured due to expiratory nature of CT scan. Bronchoscopy revealed collapsible proximal airways with complete collapse upon coughing and near complete collapse of bilateral main stem bronchi with tidal volume breathing. The patient was diagnosed with Mounier-Kuhn syndrome based on clinical history, bronchoscopy findings and tracheal diameters greater than 25mm and 27mm in the transverse and sagittal planes respectively(2).
DISCUSSION: Mounier-Kuhn Syndrome is a rare condition with roughly 100 cases reported in the literature since 1932. This diagnosis should be considered in males in their third to fourth decade of life with a history of recurrent respiratory infections, tracheomalacia and bronchiectasis(1).
CONCLUSIONS: This case demonstrates how the misdiagnosis of a rare condition can persist if symptoms are not serious enough to warrant chasing zebras. As doctors in training, we are often reminded to stop chasing zebras; however, if a compliant patient is treated appropriately without the expected response, further investigation and consideration of misdiagnosis is warranted. Mounier-Kuhn Syndrome can be easily diagnosed with CT imaging measurement of central airway diameters.
1) Menon B et al. Mounier-Kuhn syndrome: a report of 8 cases of tracheobronchomegaly with associated complications. South Med J 2008;101(1):83-7.
2) Woodring JH et al. Congenital tracheobronchomegaly (Mounier-Kuhn syndrome): A report of 10 cases and review of the literature. J Thoracic Imaging 1991;6(2):1-10.
DISCLOSURE: The following authors have nothing to disclose: Noreen Murphy, Trina Hollatz
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