Medical Image of the Month: Mounier-Kuhn Syndrome

Figure 1. AP chest x-ray showing significant tracheomegaly (diameter 30.8 mm), bilateral interstitial infiltrates with dense consolidation more at the lower lobes (left>right).

Figure 2. Axial thoracic CT in lung windows (A-D) and soft tissue windows (E-F). Sagittal CT in soft tissue windows (G-H). A: tracheal diameters in 2 dimensions (coronal 30.4 mm, sagittal 37.6 mm), para-septal emphysema (yellow arrows). B: showing tracheomegaly (23.2 x 34.3 mm) and para-septal emphysema changes (yellow arrows. C: enlarged mainstem bronchi diameters (right mainstem 22.3 x 30.6 mm, left mainstem 24.4 x 16.0 mm). In addition to central bronchiectatic changes (red arrows), left lower lobe consolidative changes (blue arrow). D: dense left lower lobe consolidation and para-septal emphysema. E: Significant tracheomegaly (31.5 x 41.a mm) and dilated esophagus (orange arrow). F: Significant tracheomegaly and dilated esophagus.

Figure 3. A: Sagittal CT scan (soft tissue window) showing significant tracheomegaly (sagittal diameter 35.8 mm). B: Sagittal CT chest (lung window) showing significant tracheomegaly, multiple tracheal diverticuli (green arrows) on the upper posterior tracheal wall.

Figure 4. Pulmonary function testing.

A 52-year-old non-smoking, Caucasian male patient with a past medical history of reported chronic obstructive pulmonary disease (COPD), recurrent lower respiratory tract infections, prior history of pneumothorax, and dysphagia presented with fevers and shortness of breathing associated with a productive cough for one week. Clinically, he was mildly tachypneic and chest auscultation revealed crackles bilaterally - more prominent at the left base. A chest radiograph (Figure 1) showed bilateral lower lobe pulmonary opacities (left more than right). Computed tomography (CT) of the chest demonstrated airspace disease in the lower lobes in addition to significant tracheobronchomegaly along with paraseptal emphysema and central bronchiectatic changes (Figures 2 and 3). Upper posterior tracheal wall diverticulae were also noted (Figure 3). Serum α₁-antitrypsin level and serum immunoglobulins, including IgE levels, were normal. Our patient declined performing diagnostic bronchoscopy. He had a pulmonary function test performed few months prior to his hospital admission which showed combined mild obstructive/restrictive pattern (Figure 4). He responded well to empiric antibiotics and chest percussion therapy. He was discharged in stable condition.

Discussion

On the basis of above findings, a diagnosis of Mounier-Kuhn syndrome complicated by pneumonia was made. The syndrome was first described by P. Mounier-Kuhn in 1932 (1). The diagnosis is usually made when the tracheal diameter is greater than 3 cm on a CT chest (measured 2 cm above the aortic arch) (2). Other diagnostic criteria include a mainstem bronchial diameter of 20-24 mm (right) and 15-23 mm (left) (3). Our patient’s tracheal diameter was around 37 mm. Both mainstem bronchi were dilated.

The abnormal tracheobronchial dilatation in this syndrome is attributed to atrophy of the muscular and elastic tissues in the tracheal and the bronchial walls (3). Hence, in addition to tracheobronchomegaly, these patients can also develop tracheal diverticulosis along with varicose and cystic bronchiectasis (3). These patients usually present in the 3rd or 4th decade of life with nonspecific respiratory symptoms including recurrent bronchitis and subsequently end up being misdiagnosed with COPD (3).

Three subtypes of this syndrome had been described. Subtype 1 has symmetric dilation of the trachea and mainstem bronchi. Subtype 2 demonstrates tracheal dilation and tracheal diverticula. Subtype 3 has diverticular and saccular structures extending to the level of the distal bronchi (3). Our patient likely fits subtype 3 of this syndrome. Overall, treatment is supportive - usually with antibiotics, physiotherapy and postural drainage. In rare instances, tracheal stenting has been used (4). Special consideration should be taken post intubation as achieving good cuff seal can be potentially challenging.

Dysphagia has not been well documented in this syndrome and could be a coincidental finding in our case. However, theoretically, the etiology of this patient’s dysphagia could be secondary to extrinsic compression of the anterior esophageal wall by his markedly dilated trachea. Historically, he underwent multiple esophageal dilatations and at least one Botox injection over the last 5 years without any significant improvement.

Abdulmonam Ali MD and Naga S. Sirikonda MD

Pulmonary and Critical Care

Good Samaritan Hospital

Mount Vernon, Illinois

References

1. Mounier-Kuhn P. "Dilatation de la trachee: constatations, radiographiques et bronchoscopies." Lyon Med. 1932;150:106-9.
2. Menon B, Aggarwal B, Iqbal A. Mounier-Kuhn syndrome: report of 8 cases of tracheobronchomegaly with associated complications. South Med J. 2008;101(1):83-7. [CrossRef] [PubMed]
3. Falconer M, Collins DR, Feeney J, Torreggiani WC. Mounier-Kuhn syndrome in an older patient. Age Ageing. 2008;37(1):115-6. [CrossRef] [PubMed]
4. Schwartz M, Rossoff L. Tracheobronchomegaly. Chest 1994;106(5):1589-90. [CrossRef] [PubMed]

Cite as: Ali A, Sirikonda NS. Medical image of the month: Mounier-Kuhn syndrome. Southwest J Pulm Crit Care. 2019;19(2):73-5. doi: https://doi.org/10.13175/swjpcc044-19 PDF 

Medical Image of the Week: Esophageal Perforation

Figure 1. Axial, non-contrast CT of chest demonstrates wall thickening of the mid-thoracic esophagus with an extra-luminal focus of gas (blue arrow) in the mediastinum in addition to a small amount of right peri-esophageal fluid (red arrow).

Figure 2. Sagittal, non-contrast CT of chest demonstrates extra-luminal air posterior to the mid-thoracic esophagus (blue arrows).

A 74 year old man with a past medical history of esophageal strictures status post dilatation, coronary artery disease status post CABG, and atrial fibrillation presented to hospital with complaints of severe chest pain that began after the consumption of tortilla chips one hour prior to presentation. Electrocardiogram and cardiac enzymes were not consistent with acute coronary syndrome. Chest X-ray was consistent with a widened mediastinal silhouette. Contrast esophogram was negative for extra luminal extravasation. CT scan of the chest with oral contrast demonstrated thickening of the mid-thoracic esophagus with an extra-luminal focus of gas in the mediastinum along with fluid along the inferior aspect of the esophagus (Figures 1 and 2). These findings were concerning for esophageal perforation. The patient was taken to the operating room for endoscopy which showed micro perforation in mid-esophagus.

Esophageal perforation remains a highly morbid condition. Mortality rates are based predominantly on time of presentation and the etiology of perforation. Symptoms of esophageal perforation are non-specific and include neck or chest pain, dysphagia, odynophagia, difficulty breathing, vomiting, drooling, hematemesis, and abdominal rigidity (1) Initial diagnostic assessment includes conventional radiography, which can be normal in up to 10% of patients. Follow-up contrast esophograms are used to determine the presence and precise location of an esophageal perforation. However, false negative rates of 10% have been reported (2). CT scan of the chest or abdomen is indicated when contrast esophogram cannot be performed or all other diagnostic modalities have not been helpful in diagnosing esophageal perforation despite high clinical suspicion. Extra-luminal air in the mediastinum or surrounding the esophagus is the most reliable sign and when taken in conjunction with the clinical presentation, has 92% accuracy. Other common findings include obliteration of fat planes in the mediastinum resulting from inflammation, peri-esophageal or mediastinal fluid (92% accuracy), esophageal thickening, pleural effusions, extravasation of oral contrast material into the peri-esophageal tissues, and a tract at the site of the tear (3).

Jawad Bilal MD, David Testa MD, Irbaz bin Riaz MD and Ryan Nahapetian MD MPH

University of Arizona

Tucson, AZ

References

1. Aronberg RM, Punekar SR, Adam SI, Judson BL, Mehra S, Yarbrough WG. Esophageal perforation caused by edible foreign bodies: A systematic review of the literature. Laryngoscope. 2015;125(2):371-8. [CrossRef] [PubMed]
2. Bladergroen MR, Lowe JE, Postlethwait RW. Diagnosis and recommended management of esophageal perforation and rupture. Ann Thorac Surg. 1986;42(3):235-9. [CrossRef] [PubMed]
3. Lee S, Mergo PJ, Ros PR. The leaking esophagus: CT patterns of esophageal rupture, perforation, and fistulization. Crit Rev Diagn Imaging. 1996;37(6):461-90. [PubMed] 

Reference as: Bilal J, Testa D, Riaz I, Nahapetian R. Medical image of the week: eosphageal perforation. Southwest J Pulm Crit Care. 2015;10(4):201-2. doi: http://dx.doi.org/10.13175/swjpcc033-15 PDF