AJR 2001; 176:713-717
© American Roentgen Ray Society
Diffuse Abnormalities of the Trachea and Main Bronchi
Edith M. Marom1,
Philip C. Goodman and
H. Page McAdams
1
All authors: Department of Radiology, Box 3808, Duke University Medical
Center, Durham, NC 27710.
Received June 29, 2000;
accepted after revision August 14, 2000.
Address correspondence to E. M. Marom.
Introduction
Abnormalities of the central airways may produce symptoms such as cough,
dyspnea, wheezing, or stridor, but there is frequently a delay in diagnosis.
If central airways abnormalities are clinically suspected, further evaluation
of tracheobronchial lesions is best performed with CT. A variety of diseases
may affect the airways, resulting in either focal or diffuse narrowing or
enlargement. This pictorial essay focuses on diffuse abnormalities of the
major airways. We recognize that the distinction of diffuse from focal airway
abnormalities is somewhat arbitrary and is complicated by the fact that many
diseases can cause either focal or diffuse airway narrowing. For purposes of
this review, however, we will discuss only those diseases that most commonly
result in long-segment or multifocal airway disease.
Diffuse Airway Narrowing
Diffuse narrowing of the trachea or main bronchi may result from relapsing
polychondritis, ulcerative colitis, amyloidosis, sarcoidosis, Wegener's
granulomatosis, tracheopathia osteochondroplastica, and various infections
including papillomatosis. Occasionally, malignancies manifest with diffuse
rather than focal airway narrowing.
Relapsing polychondritis is an autoimmune connective tissue disease
characterized by polyarthritis, aortitis or arteritis, uveal inflammation and
recurrent cartilage inflammation, particularly of the ears, nose, larynx, and
trachea and mainstem bronchi (up to 70% of affected individuals)
[1]. Recurrent pulmonary
infection is the most common cause of morbidity and mortality in these
patients [2,
3]. Radiologic manifestations
include longsegment tracheobronchial strictures, mural thickening, and
calcification (Fig. 1A).
Expiratory collapse of the affected airway may be revealed on fluoroscopy or
dynamic CT (Figs. 1B and
1C). Similar findings are
rarely seen in patients with ulcerative colitis
[4].
View larger version (139K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B. —Relapsing polychondritis in 49-year-old woman. Inspiratory CT
scan (lung window settings, 10-mm collimation) reveals thickened anterior
cartilaginous portion of bronchi (arrows) and normal lung
parenchyma.
|
|
Tracheobronchial amyloidosis most commonly manifests as diffuse mural
thickening and luminal narrowing. Less commonly, solitary or multiple mural
nodules are seen [5]. Mural
calcification may be evident on CT (Fig.
2).
View larger version (107K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2. —Amyloidosis in 27-year-old woman with progressive dyspnea. CT
scan (1.5-mm collimation) obtained at level of left main bronchus depicts
diffuse circumferential thickening of bronchial walls (arrows). Note
high-attenuation regions in bronchial wall, likely representing calcification.
Transbronchial biopsy revealed amyloidosis.
|
|
Endobronchial granulomata in patients with sarcoidosis may rarely (1% of
cases) result in significant airway narrowing and lobar atelectasis
[6]
(Fig. 3).
View larger version (101K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3. —Sarcoidosis in 30-year-old woman. Coronal
minimum-intensity-projection image obtained from CT scan (3-mm collimation)
reveals diffuse narrowing of left main bronchus (straight arrows) and
its bifurcating branches, surrounded by conglomerate mediastinal and left
hilar lymphadenopathy. Note occlusion of left upper lobe bronchus (curved
arrows) by same process. L = left main bronchus, r = right main
bronchus.
|
|
Wegener's granulomatosis produces airway abnormalities in 59% of patients
as seen at bronchoscopy. Tracheal strictures affect 7% of patients
[7]. CT depicts focal or
diffuse wall thickening and airway narrowing (Figs.
4A,4B
and 5). The cartilaginous
tracheal rings may calcify [2].
When evaluating tracheal stenosis due to Wegener's granulomatosis, the larynx
should be included because focal stenosis from Wegener's granulomatosis most
commonly affects the subglottic trachea.
View larger version (100K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A. —Wegener's granulomatosis in 19-year-old man with dyspnea. CT
scan (3-mm collimation) obtained at level of thyroid gland (T) reveals
significant tracheal narrowing with diffuse circumferential soft-tissue
thickening.
|
|
View larger version (46K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B. —Wegener's granulomatosis in 19-year-old man with dyspnea.
Lateral shaded-surface—display image obtained from CT scan (3-mm
collimation) reveals diffuse narrowing of subglottic trachea (solid
arrows) that extends 1.5 cm inferiorly from vocal cords. Note apparent
airway discontinuity due to adducted vocal cords (open arrows). p =
pyriform sinus.
|
|
View larger version (110K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5. —Wegener's granulomatosis in 33-year-old woman. Coronal
minimum-intensity-projection image obtained from CT scan (3-mm collimation)
delineates two focal strictures (arrows) in diffusely narrowed left
main bronchus.
|
|
Tracheopathia osteochondroplastica is a rare idiopathic and usually
asymptomatic disorder of older men; this disorder is characterized by multiple
osteocartilaginous masses adjacent to the tracheal rings of the inner
anterolateral wall of the trachea. Tracheopathia osteochondroplastica is
distinguished from tracheobronchial amyloidosis or relapsing polychondritis
because it does not involve the posterior membranous portion of the trachea
[1,
2]. Radiologically, focal
tracheal thickening, calcification of the tracheal rings, multiple calcified
tracheal nodules, and long-segment tracheal narrowing are typically seen (Fig.
6A,6B).
View larger version (81K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6A. —Tracheopathia osteochondroplastica in 75-year-old
asymptomatic man. (Courtesy of CA Meyer, Indianapolis, IN) CT scan (10-mm
collimation) obtained at level of transverse aorta reveals multiple calcified
nodules arising from inner anterolateral wall of trachea. Posterior membranous
portion of trachea (arrow) is spared. Note lymph node (n) is
calcified, which was likely caused by prior histoplasmosis.
|
|
View larger version (97K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6B. —Tracheopathia osteochondroplastica in 75-year-old
asymptomatic man. (Courtesy of CA Meyer, Indianapolis, IN) CT scan (lung
window settings) shows diffuse mural nodules involving only cartilaginous
portion of bronchi resulting in mild luminal narrowing.
|
|
Tracheobronchial papillomatosis is caused by the human papillomavirus,
usually acquired at birth from an infected mother. Dissemination of upper
airway and laryngeal lesions occurs in 5% of patients and results in multiple
nodules projecting into the airways. The papillomas are benign but may undergo
malignant transformation to squamous cell carcinoma
[8]. Chest radiography or CT
may reveal intraluminal masses, parenchymal nodules (after distal airway
dissemination), air-filled cysts (pneumatoceles), or thick-walled cavities
(Fig. 7).
View larger version (115K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7. —Tracheobronchial papillomatosis in 49-year-old woman with
laryngeal papillomata. CT scan (10-mm collimation) reveals 6-mm intratracheal
nodule consistent with tracheal papilloma (arrow). Tracheobronchial
tree was diffusely studded with smaller papillomata.
|
|
Other infections such as tuberculosis, coccidioidomycosis, histoplasmosis
(Fig.
8A,8B),
mucormycosis, and Klebsiella rhinoscleromatis can lead to airway
narrowing that is more commonly focal than diffuse
[7].
View larger version (117K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8A. —Histoplasmosis in 45-year-old man with recurrent pneumonia in
right lung. CT scan (3-mm collimation) shows significant narrowing of bronchus
intermedius (straight arrow), adjacent soft-tissue mass, and heavily
calcified subcarinal lymph node (curved arrow).
|
|
View larger version (127K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8B. —Histoplasmosis in 45-year-old man with recurrent pneumonia in
right lung. Coronal oblique shaded-surface—display image obtained from
CT scan (3-mm collimation) shows diffuse narrowing of bronchus intermedius
(arrow). L = left main bronchus, R = right main bronchus.
|
|
An important mimic of diffuse tracheal narrowing is the saber-sheath
trachea deformity. This entity is a pathognomonic finding in patients with
chronic obstructive pulmonary disease. The saber-sheath appearance is found
when mechanical forces of hyperinflated lungs cause the coronal diameter of
the intrathoracic trachea to narrow and the sagittal diameter to elongate so
that the sagittal-to-coronal diameter ratio exceeds 2:1. The extrathoracic
trachea remains normal in configuration. CT may also reveal mild intrathoracic
tracheal wall thickening, frequently with ossification of the tracheal rings
[2,
7] (Fig.
9A,9B,9C).
View larger version (103K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9A. —Saber-sheath trachea in 64-year-old man with chronic
obstructive pulmonary disease. Posteroanterior chest radiograph reveals
diffuse narrowing of coronal diameter of intrathoracic trachea (straight
arrows). Note that extrathoracic trachea is normal in diameter
(curved arrow).
|
|
View larger version (117K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9B. —Saber-sheath trachea in 64-year-old man with chronic
obstructive pulmonary disease. Lateral chest radiograph shows increased
tracheal diameter throughout its intrathoracic course (arrows).
|
|
View larger version (118K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9C. —Saber-sheath trachea in 64-year-old man with chronic
obstructive pulmonary disease. CT scan (10-mm collimation) obtained at
thoracic inlet reveals that sagittal diameter—coronal diameter ratio of
intrathoracic trachea exceeds 2:1. Tracheal walls are mildly thickened with
ossification of tracheal rings.
|
|
Diffuse Airway Enlargement (Tracheobronchomegaly)
Tracheobronchomegaly is defined as a transverse and sagittal tracheal
diameter exceeding 25 and 27 mm, respectively, or the left and right mainstem
bronchi exceeding 18 or 21 mm in diameter, respectively, in men. The
respective figures for women are 21, 23, 17.4, and 19.8 mm
[2]. Conditions that can result
in tracheobronchomegaly include congenital disorders such as Mounier-Kuhn's
and Ehlers-Danlos syndromes; diseases that result in severe upper lobe
fibrosis such as sarcoidosis and cystic fibrosis; and inflammatory disorders
of the airways such as allergic bronchopulmonary aspergillosis.
Mounier-Kuhn's syndrome is thought to result from a congenital deficiency
in the internal elastic membrane of the trachea and central bronchi. The
disease is diagnosed in most patients during the fourth or fifth decade of
life; men are more commonly affected than women. Patients usually present with
signs and symptoms related to recurrent infection and bronchiectasis.
Radiologic findings of an irregular air column reflect the
"corrugated" effect that is produced when redundant mucosa
prolapses through the tracheal rings (Fig.
10A,10B,10C).
Tracheobronchial diverticula and central bronchiectasis also occur, and CT
scans reveal these abnormalities better than chest radiographs. Expiratory
studies may reveal collapse of the major airways
[2,
7]. Mounier-Kuhn's syndrome may
be confused with Williams-Campbell syndrome, a rare form of congenital cystic
bronchiectasis that results from a deficiency of cartilage in the fourth- to
sixth-order bronchi (Fig. 11).
Although both diseases can result in significant bronchiectasis, patients with
Williams-Campbell syndrome have normal-caliber trachea and main bronchi
[2].
View larger version (132K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10A. —Mounier-Kuhn's syndrome in 42-year-old man who presented with
recurrent pneumonia. Posteroanterior chest radiograph shows marked tracheal
(straight arrows) and bronchial enlargement (curved
arrows).
|
|
View larger version (96K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10B. —Mounier-Kuhn's syndrome in 42-year-old man who presented with
recurrent pneumonia. CT scan (8-mm collimation) reveals marked enlargement of
main bronchi with corrugated appearance of anterior bronchial wall from
mucosal prolapse through tracheal rings (arrow).
|
|
View larger version (84K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10C. —Mounier-Kuhn's syndrome in 42-year-old man who presented with
recurrent pneumonia. CT scan (8-mm collimation) confirms marked enlargement of
trachea (T), measuring 3.9x3.5 cm in diameter.
|
|
View larger version (107K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 11. —Williams-Campbell syndrome in 27-year-old man with recurrent
infection. Thin-section CT scan (1.5-mm collimation) shows varicoid and cystic
central bronchiectasis associated with normal-caliber main bronchi.
|
|
Pulmonary fibrosis in the upper lobes causes retraction of the
tracheobronchial walls, leading to tracheomegaly
(Fig. 12). Chronic airway
inflammation or infection, most commonly caused by smoking, chronic
bronchitis, emphysema, and cystic fibrosis
[7], may result in
tracheobronchomalacia; patients with tracheobronchomalacia present with a
diffusely flaccid and dilated airway.
View larger version (102K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 12. —Traction tracheomegaly in 63-year-old man with prior history
of tuberculosis. Posteroanterior chest radiograph shows severe upper lobe
fibrosis resulting in displacement and dilatation of trachea (curved
arrows) and main bronchi (straight arrows).
|
|
Allergic bronchopulmonary aspergillosis and cystic fibrosis, like
Mounier-Kuhn's syndrome, may produce predominant enlargement of the central
bronchi or central bronchiectasis. Allergic bronchopulmonary aspergillosis
results from airway colonization by Aspergillus species and the
subsequent immunologic response to aspergillus antigens. It usually occurs in
patients with chronic asthma or cystic fibrosis. The diagnosis is suggested by
radiologic visualization of central, round, or varicoid bronchiectasis; large
mucoid impactions; and fleeting peripheral air-space opacities
[2,
9]
(Fig. 13).
Summary
Airway lesions are frequently overlooked clinically and radiographically,
but if they are suspected, the differential diagnosis for these diseases is
limited. The increased use of chest CT to delineate lung abnormalities may
lead to the incidental detection of more tracheobronchial abnormalities.
Familiarity with the appearances of more typical airway abnormalities should
improve diagnosis and patient care.
References
-
Meyer CA, White CS. Cartilaginous disorders of the chest.
RadioGraphics
1998;18:1109
-1123[Abstract]
-
Fraser RS, Muller NL, Colman N, Pare PD. Diagnosis of
diseases of the chest, 4th ed. Philadelphia: Saunders,
1999
-
Michet CJ Jr, McKenna CH, Luthra HS, O'Fallon WM. Relapsing
polychondritis: survival and predictive role of early disease manifestations.
Ann Intern Med
1986;104:74
-78
-
Wilcox P, Miller R, Miller G, et al. Airway involvement in
ulcerative colitis. Chest
1987;92:18
-22[Abstract/Free Full Text]
-
Kim HY, Im JG, Song KS, et al. Localized amyloidosis of the
respiratory system: CT features. J Comput Assist
Tomogr 1999;23:627
-631[Medline]
-
Freundlich IM, Libschitz HI, Glassman LM, Israel HL. Sarcoidosis:
typical and atypical thoracic manifestations and complications.
Clin Radiol
1970;21:376
-383[Medline]
-
Stark P. Radiology of the trachea.
Stuttgart, Germany: Thieme, 1991:54
-78
-
Gruden JF, Webb R, Sides DM. Adult-onset disseminated
tracheobronchial papillomatosis: CT features. J Comput Assist
Tomogr 1994;18:640
-642[Medline]
-
Lynch DA. Imaging of asthma and allergic bronchopulmonary mycosis.
Radiol Clin North Am
1998;36:129
-142[Medline]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
K. S. Lee, A. Ernst, D. E. Trentham, W. Lunn, D. J. Feller-Kopman, and P. M. Boiselle
Relapsing Polychondritis: Prevalence of Expiratory CT Airway Abnormalities
Radiology,
August 1, 2006;
240(2):
565 - 573.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. Tadjeddein, Z. Khorgami, and H. Akhlaghi
Tracheobronchopathia Osteoplastica: Cause of Difficult Tracheal Intubation
Ann. Thorac. Surg.,
April 1, 2006;
81(4):
1480 - 1482.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. V. Behar, Y.-W. Choi, T. A. Hartman, N. B. Allen, and H. P. McAdams
Relapsing Polychondritis Affecting the Lower Respiratory Tract
Am. J. Roentgenol.,
January 1, 2002;
178(1):
173 - 177.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. E. Rossi, H. P. McAdams, M. L. Rosado-de-Christenson, T. J. Franks, and J. R. Galvin
Fibrosing Mediastinitis
RadioGraphics,
May 1, 2001;
21(3):
737 - 757.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Introduction
Diffuse Airway Narrowing
