Thoracic Imaging 2003 - Society of Thoracic Radiology

onchi. The nodules may be either focal or diffuse, characteristically,
these nodules spare the membranous posterior wall of
the trachea. There is a 3:1 male predilection and the disease
typically manifests between fifth and sixth decades. The disease
usually remains asymptomatic and may be detected on
bronchoscopy performed for another reason. The prevalence of
TO found during routine bronchoscopy for unrelated complaints
ranges from 0.02% to 0.7%. When symptomatic, TO has been
reported to cause recurrent infection, cough, stridor and hemoptysis.
The evolution of the disease is usually slow and prognosis
depends on the extent of the disease.
The characteristic CT appearance consists of calcified nodules
measuring between 3 and 8mm in diameter resulting in
irregular narrowing of the lower trachea and main stem bronchi
with sparing of the posterior tracheal wall.
At bronchoscopy, these nodules are typically hard and difficult
to biopsy. The diagnosis is made from the visual appearance
alone. There is currently no specific treatment to remove
the abnormal tissue growth or to prevent the development of
new nodules.
RELAPSING POLYCHONDRITIS
Relapsing polychondritis is a rare inflammatory disease of
unknown cause involving the cartilage of nose, ears, upper respiratory
tract, and the joints. It is thought to be related to
abnormal acid mucopolysaccharide metabolism, an association
has also been noted in approximately 25% of cases with autoimmune
vasculitis.
Histologically, there is evidence of chondritis with perichondral
inflammation, loss of basophilic staining of cartilage matrix
and fibrous replacement of damaged cartilage. Clinically auricular
chondritis is seen in 88% of patients. Nasal chondritis is
less frequent. Polyarthritis occurs in 76% of the patients. The
respiratory tract is affected in 56-70% of cases and carriers a
poor prognosis, accounting for 50% of deaths.
Characterized by episodic inflammation, relapsing polychondritis
results in diffuse tracheal and bronchial narrowing secondary
to a combination of edema, granulation tissue, cartilage
destruction and ultimately fibrosis of the tracheal wall. When
severe, this disease may result in airway obstruction and recurrent
episodes of atelectasis and pneumonia.
At radiography, diffuse or localized airway involvement may
be seen. The larynx and upper trachea are affected most frequently,
but disease may involve airways to the subsegmental
level.
Trachea narrowing resulting from thickening of the anterior
and lateral walls with sparing of the posterior tracheal wall is
characteristic. Dynamic imaging during expiration may demonstrate
airway collapse.
AMYLIODOSIS
Amyloidosis is characterized by the deposition of abnormal
proteinaceous material (amyloid) in extra cellular tissue that
characteristically stains with Congo red. Amyloid infiltration of
the airways and lung may occur as an isolated phenomenon or
as part of diffuse systemic disease. Three patterns of respiratory
involvement have been described; (a) tracheobronchial, (b)
nodular parenchymal disease, (c) diffuse parenchymal disease.
The tracheobronchial pattern is the most common pattern of respiratory
amyloidosis. Tracheobronchial amyloidosis is rare and
is generally confined to the trachea without evidence of concurrent
parenchymal disease. Deposits may be either solitary or
multiple, with or without calcifications, and if sufficiently large,
they can lead to hemoptysis or airway obstruction with resultant
atelectasis or recurrent pulmonary infection.
The classic radiographic appearance of tracheobronchial
amyloidosis is nodular and irregular narrowing of the tracheal
lumen. Lobar or segmental collapse may be seen with endobronchial
obstruction due to amyloid deposition. In certain
cases of diffuse involvement, there is significant component of
calcification and ossification of the lesions. Unlike tracheopathia
osteochondroplastica, in which nodules spare the
membranous portion of trachea, amyloidosis involves the entire
circumference of the trachea.
ULCERATIVE COLITIS
Rare involvement of both large and small airways has been
reported to occur in patients with ulcerative colitis. Findings of
submucosal fibrosis and airway narrowing have been described,
including the trachea, often in association with bronchiectasis.
To date no apparent relationship has been established between
disease activity within the colon and airway abnormalities.
On CT, the tracheobronchial walls appear thickened, resulting
in an irregular narrowing.
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Daun TE, Specks U, Colby TV, Edell ES et al: Tracheobronchial
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Port JL, Khan A, Barbu RR: Computed Tomography of Relapsing
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Pickfor HA, Swensen SJ, Utz JP: Thoracic Cross-Sectional
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THURSDAY