Clinical and Radiological Manifestations of Congenital Tracheobronchomegaly (Mounier - Kuhn Sydrome)
Igor Kocijancic1, MD, PhD; Pavel Kavcic*1, MD
1Clinical Radiology Institute, University Medical Centre Ljubljana, Slovenia
Mounier-Kuhn Syndrome is a rare congenital abnormality characterized by pathological dilation of the trachea and major bronchi, often accompanied with tracheal diverticulosis, bronchiectasis, bullae and recurrent pulmonary infections. It was first described by a french physician Pierre Mounier Kuhn in 1932 . The incidence was estimated to be in the range of 0.5 to 1.5% with male preponderance . The cause of the condition is not clearly understood; however, in biopsy studies, the absence or marked atrophy of the elastic fibers and smooth muscle of the trachea and main bronchi has been observed. Symptoms can range from minimal with preserved lung function to severe respiratory failure. Since clinical picture is non-specific, diagnosis is made radiologically. Chest radiography may establish the diagnosis if tracheal dilatation is evident; however, CT is usually required for accurate airway measurement and to assess complications. Early recognition is important as it can lead to better management and prevention of complications.
Figure 1. Coronal and axial chest CT showing tracheobronchomegaly.
Figure 2. Coronal and axial chest CT showing multiple diverticula.
The patient was ex-smoker with no occupational exposure to respiratory irritants. There was no family history of a lung illness. Pulmonary function test were normal. Previous chest radiographs were stated to be normal, without any pulmonary infiltrates.
Figure 3. Coronal and axial chest CT showing bullous emphysema. Chest CT scan showed evident tracheobronchomegaly. The trachea was dilated, with a diameter of 3.4 cm, while the right and left main bronchi had diameters of 2.1 and 2.3 cm, respectively. Multiple diverticula and areas of scalloping were seen between the cartilaginous rings in the trachea and in right and left main bronchi. The largest posterior tracheal diverticula was measuring 2x1 cm. Additional bullous emphysema and several cystic bronchiectasis were seen in the lung parenchyma bilaterally (Figures 1-3).
Mounier-Kuhn syndrome is a rare congenital abnormality of unknown cause that is characterized by marked dilatation of the trachea and main bronchi, often accompanied with tracheal diverticulosis, emphysematous bullae, bronchiectasis, and recurrent pulmonary infections. The underlying abnormality is the absence or marked atrophy of the elastic fibers and smooth muscle within the wall of trachea and main bronchi. These airways are thus flaccid and markedly dilated on inspiration with narrowing or collapse on expiration or cough. The abnormal airway dynamics predisposes to mucosal herniation between tracheal rings, leading to tracheal diverticulosis and promoting frequent bacterial colonization. There is also increase in dead space and tidal volume. The airways distal to the fourth-order division are usually normal in diameter.
The condition is more common in men and is typically diagnosed in the 3rd or 4th decades of life . Although the majority of cases appear to be sporadic, a familial form has been described . Secondary tracheobronchomegaly was also described in association with Ehlers-Danlos syndrome, Marfan syndrome, Kenny-Caffey syndrome, cutis laxa in children and
Cite this article: Kavcic P. Clinical and Radiological Manifestations of Congenital Tracheobronchomegaly (Mounier - Kuhn Sydrome). J J Pulmonol. 2015, 1(1): 001.