diagnosis by Doppler echocardiography. Cardiology 1990;77:472-76

7 Schluter M, Langenstein BA, Thier W. Transesophageal two-dimensional echocardiography in the diagnosis of cor triatria-tum in the adult. J Am Coll Cardiol 1983; 2:1011-1015

8 Sechtem U, Pflugfelder PW, Gould RG, Holt W, Lipton MJ,Higgins CB. Cine MR imaging: potential for the evaluation ofcardiovascular function. Am J Radiol 1987; 148:239-246

Tracheobronchomegaly*Marlene Schwartz, M.D.; and Leonard Rossoff, M.D.

We report two cases of tracheobronchomegaly withdiffering presentations. The radiologic, fiberoptic bron-choscopic, and clinical findings as well as managementof this rare condition are reviewed.

(Chest 1994; 106:1589-90)

CT=computed tomography; TBM=tracheobronchomegalyFIGURE 1. The PA view of the trachea on the x-ray reveals severedilatation of the trachea.

Tracheobronchomegaly (TBM) or the Mounier-Kuhnsyndrome is a rare condition characterized by marked

dilatation of the trachea and major bronchi and chronicrespiratory infections. We report an additional two caseswith differing clinical presentations.

CASE REPORTSCASE 1A 71-year-old man with a 30-pack-year history of cigarette

smoking, long-standing bronchiectasis, and recurrent pneumoniaspresented with respiratory failure requiring mechanical ventila-tion. Fiberoptic bronchoscopy, for unresolving infiltrates, re-vealed copious thick secretions and markedly enlarged airways.The tracheobronchial mucosa was edematous and corrugatedwith multiple redundant folds, crypts, and diverticula. He wassuccessfully extubated but has required continuous home oxygen,frequent antibiotics, and vigorous postural drainage. Postextuba-tion chest radiograph (Fig 1) clearly shows the findings of TBM.

CASE 2A 61-year-old man, 30-pack-year smoker with mild ankylosing

spondylitis presented with 1 month of progressive exertionaldyspnea and cough productive of mucopurulent sputum. He de-nied all constitutional complaints. Initial roentgenogram showedbilateral lower lobe infiltrates and pleural thickening. Despite twoweeks of outpatient antibiotics, the infiltrates progressed andfailed to resolve with an additional week of inpatient intravenousantibiotics. All sputum smears, cultures, and cytology were neg-ative. Bronchoscopy results suggested submucosal atrophy andchondromalacia of the trachea and major bronchi. Computedtomography (CT) scan of the chest (Fig 2) revealed paraseptal,panlobular, and centrilobular emphysema, extensive bronchiecta-sis, interstitial fibrosis of the lower lobes, and chronic pleuralthickening. Enlargement of the trachea and major bronchi wasalso noted.*From the Division of Pulmonary/Critical Care, Long IslandJewish Medical Center, The Long Island Campus for the AlbertEinstein College of Medicine, New Hyde Park, New York.

DISCUSSIONMarked tracheobronchial dilatation in association with

lower respiratory tract infections was first reported byMounier-Kuhn in 1932. A review of the world literature to1988 by Shin et all revealed only 82 cases. The identifica-tion of some patients with minimal or no symptoms sug-gests the syndrome's incidence may be greater thansuspected.The radiologic diagnosis of TBM requires recognition of

normal airway diameters but potential variability ofmagnification have led to disagreement.2 Himalstein andGallagher3 measured the diameters of the tracheal andmainstem bronchial lumens at autopsy in 100 men with no

FIGURE 2. The CT scan of the chest at the level of the carina re-veals bronchial dilatation, bronchiectasis, and emphysematouschanges.

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known tracheobronchial abnormality. The mean trans-verse diameter of the trachea, just above the carina, was 19mm with an upper limit of normal of 28.6 mm. The meansagittal diameter was 16.9 mm with an upper limit ofnormal of 24.7 mm. They found that the mean transverseand sagittal diameters of the right and left main bronchiwere 17.7 mm and 12 mm (upper limit of normal of 25.8mm and 17.4 mm) and 14.4 mm and 11.2 mm (upper limitof normal of 22.5 and 16.3 mm) respectively.The TBM is characterized by severe atrophy of longi-

tudinal elastic fibers with thinning of the muscularis mu-cosa, which results in dilation of the membranous andcartilaginous portions of the trachea and main bronchi.This increased compliance of the wall allows the develop-ment of broad divericulum like protrusions of redundantmusculomembranous tissue between the cartilaginousrings.Dynamic radiographic and endoscopic studies charac-

teristically show the trachea and major bronchi distendwith deep inspiration and collapse on expiration. Thecentral airways may virtually occlude with forced expira-tion or cough. Retention of secretions may lead to chronicinfection and some degree of chronic bronchitis, bron-chiectasis, and pulmonary fibrosis.

Tracheobronchomegaly has been classified into threesubtypes.3 In Type 1 there is relatively subtle symmetri-cally diffuse enlargement of trachea and major bronchi.Type 2 has more obvious enlargement with bizarreeccentric configurations and diverticula may also bepresent. In Type 3 diverticula or sacculations extend to thedistal bronchi.The cause of TBM is unresolved. An acquired abnor-

mality is suggested by its extreme rarity, association withchronic respiratory infections, and delayed onset. The di-agnosis is made in 75 percent of patients at age 29 or olderwith few if any symptoms reported in childhood.A genetic link is suggested by the finding of radiographic

evidence of TBM in siblings and reports in adults withEhlers-Danlos syndrome and children with cutis laxa. Ithas additionally been associated with duplication of thedistal trachea, double carina, tracheal trifurcation, andwith a congenitally short abnormal right upper-lobebronchus. 2,4The clinical manifestations of TBM are nonspecific and

largely indistinguishable from those of chronic bronchitisor bronchiectasis. It presents usually in the third or fourthdecade of life (range 18 months to 76 years). Many patientshave few or no symptoms and no apparent progression ofdisease. Some, however, follow a course of chronic recur-rent pulmonary infection. There is often a harsh cough,copious purulent sputum, occasional hemoptysis, and pro-gressive dyspnea. It is likely, that once established, infec-tion accelerates the damage of the tracheobronchial tree.Pulmonary function tests often show an increased dead

space and tidal volume. Airflow limitation with increasedtotal lung capacity and residual volume are common.Subsequent fibrosis may result in superimposed restrictivepattern.

As in bronchiectasis, CT scan has replaced bronchogra-phy in confirming the diagnosis. Routine radiographs alonemay adequately display the tracheobronchomegaly and

saccular outpouchings (Fig 1). The transverse streaks ofsoft tissue density may mimic the x-ray film appearance ofthe valvulae conniventes of the dilated small intestine.

Bronchoscopy can also confirm the diagnosis. Thegrossly dilated trachea and mainstem bronchi occasionallyhave a corrugated appearance. The membranous portionsmay be seen to protrude dramatically between the widelyseparated rings during coughing or forced expiration.

Asymptomatic patients with TBM require no specifictherapy, although smoking cessation maybe helpful. Ther-apy is primarily limited to intensive antibiotic therapy andpostural drainage. Bronchoscopy, tracheostomy or bothmay facilitate management of secretions and mucousplugging in some patients. The generalized nature of thedisease limits any possible benefits of surgical resection.

In conclusion, the diagnosis of TBM should be consid-ered in instances of recurrent pneumonia and mucousplugging with or without suggestive radiologic findings.

REFERENCES1 Shin MS, Jackson RM, Ho KJ. Tracheobronchomegaly (Mou-

nier-Kuhn syndrome): CT diagnosis. Am J Roentgenol 1988;150(4):777-79

2 Woodring JH, Howard II RS, Rehm SR. Congenital tracheo-bronchomegaly (Mounier-Kuhn syndrome): a report of 10 casesand review of the literature. J Thorac Imaging 1991; 6(2):1-10

3 Himalstein MR, Gallagher JC. Tracheobronchiomegaly. AnnOtol Rhinol Laryngol 1973; 82:223-27

4 Ratliff JL, Campbell GD, Reid MV. Tracheobronchiomegaly:report of two cases with widely differing symptomatology. AnnOtol Rhinol Laryngol 1977; 86:172-75

Aortobronchial Fistula 13 YearsFollowing Repair of AorticTransection*Ella A. Kazerooni, M.D.; David M. Williams, M.D.;Gerald D. Abrams, M.D.; G. Michael Deeb, M.D.;and John G. Weg, M.D.; F.C.C.P.

We describe a 56-year-old man with the new onset ofhemoptysis, increasing in frequency and magnitude,initially diagnosed and treated as pulmonary embolism.Bronchoscopy, computed tomography, and thoracicaortography were performed twice before the diagnosiswas made. Thirteen years previously, the patient un-derwent thoracic aortic interposition graft placementfor aortic laceration as a result of a motor vehicle acci-dent. The second aortogram demonstrated a smallpseudoaneurysm at the expected proximal graft sutureline. Aortobronchial fistula, a rare cause of hemoptysis,was diagnosed. The patient underwent successful resec-*From the Departments of Radiology (Drs. Kazerooni andWilliams), Pathology (Dr. Abrams), Surgery (Dr. Deeb), andInternal Medicine (Dr. Weg), University of Michigan Hospitals,Ann Arbor.

Reprint requests: Dr. Kazerooni, 1500 E Medical Center Drive,TCZ91OQ, Ann Arbor, MI 48109

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