International Journal of Medical Sciences And Clinical Research
59
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VOLUME
Vol.05 Issue05 2025
PAGE NO.
59-64
10.37547/ijmscr/Volume05Issue05-13
Pathomorphological Features of Congenital and
Acquired Tracheobronchomalacia
Shevketova Lilya.Shevketovna.
Andijan State Medical Institute, PhD, Uzbekistan
Makhkamov Nosirjon.Jurayevich.
Andijan State Medical Institute, DSc, Associate Professor, Uzbekistan
Received:
29 March 2025;
Accepted:
25 April 2025;
Published:
27 May 2025
Abstract:
Tracheomalacia is a pathological condition characterized by increased flaccidity of the tracheal or
bronchial walls due to underdevelopment or degeneration of the cartilaginous framework, resulting in dynamic
airway collapse during respiration. It is classified into two main types: congenital and acquired. Congenital
tracheomalacia arises due to developmental anomalies during fetal ontogenesis, while the acquired form may
result from prolonged mechanical ventilation, chronic inflammation, or external compression, but importantly,
can also originate from prenatal developmental disturbances. This ontogenetic link between congenital and
acquired forms has been increasingly recognized in recent studies, particularly when the acquired variant emerges
as a consequence of cartilaginous dysplasia during intrauterine development.
From a morphological perspective, tracheomalacia can manifest in various structural forms, including crescentic,
bow-shaped, and concentric types. In all types, there is a common feature of anatomical underdevelopment of
the tracheobronchial wall layers, especially affecting their cartilaginous and muscular components. In the
crescentic and bow-shaped variants, the mucosal integrity is typically preserved, and the primary deficiency lies
in the cartilaginous tissue. Histologically, this is expressed by a reduced number of chondrocytes, absence of
continuous cartilaginous support along more than three-quarters of the airway circumference, and the presence
of small, isolated cartilaginous islets. These anomalies lead to structural instability and dynamic collapse of the
airways, exacerbated by contraction of the bronchial smooth muscle bundles.
Understanding the morphogenetic and structural characteristics of tracheomalacia is crucial for accurate
diagnosis and appropriate therapeutic decision-making, particularly in neonates and infants presenting with
airway obstruction symptoms.
Keywords:
Tracheobronchomalacia, airway anomaly, cartilage dysplasia, congenital malformation, acquired
malacia, bronchial wall deformation, airway collapse, ontogeny, chondrocyte deficiency.
Introduction:
Tracheobronchomalacia (TBM) is a
pathological condition characterized by weakness and
excessive collapsibility of the tracheal and bronchial
walls. It manifests in two main forms: congenital and
acquired. Congenital TBM arises due to developmental
defects in the formation of the tracheobronchial
cartilage and connective tissue during the embryonic
and fetal stages, whereas acquired TBM develops
secondary to inflammation, prolonged mechanical
ventilation, trauma, or other external factors affecting
airway integrity [1, 2].
From a pathomorphological perspective, TBM is
defined by structural abnormalities in the airway walls,
primarily involving cartilage hypoplasia or dysplasia,
thinning of the mucosal and submucosal layers, and
disorganization of the elastic fibers that normally
provide mechanical stability [3, 4]. Congenital TBM
often presents as incomplete or weakened cartilage
rings, with shapes varying from semicircular and
International Journal of Medical Sciences And Clinical Research
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International Journal of Medical Sciences And Clinical Research (ISSN: 2771-2265)
crescentic to concentric deformities. These alterations
result in impaired airway patency and dynamic collapse
during respiration [5].
Acquired TBM, on the other hand, is frequently
associated with degenerative changes in the
tracheobronchial wall components due to chronic
inflammation, scarring, or external compression,
leading to loss of structural support and similar clinical
manifestations [6, 7].
Epidemiologically,
congenital
bronchopulmonary
anomalies, including TBM, account for approximately
4
–
7% of all congenital malformations in newborns,
with significant neonatal mortality rates worldwide.
The pathomorphological understanding of TBM is
essential for improving diagnostic accuracy and
developing effective therapeutic interventions to
reduce morbidity and mortality [8, 9].
Given the diverse etiology and complex morphological
changes, detailed histopathological studies are critical
to differentiate congenital and acquired TBM, to
identify their severity, and to guide appropriate clinical
management [10].
Research Objective
The objective of this study is to investigate the
pathomorphological features of congenital and
acquired tracheobronchomalacia, to identify the
structural changes in the tracheobronchial walls, and to
analyze their clinical significance in relation to neonatal
and infant respiratory morbidity and mortality. The
study aims to improve the understanding of the
developmental
mechanisms
underlying
tracheobronchomalacia and to provide insights for
better diagnosis, management, and treatment of
affected patients.
METHODS
Data and autopsy materials were collected from 113
cases referred to the Republican Center of Pathological
Anatomy with confirmed congenital anomalies.
Bronchial and lung tissues were obtained for analysis.
Using morphological methods, the tissue samples were
stained with hematoxylin and eosin (H&E), and the
structural components of the tissues were examined
and analyzed.
RESULTS AND DISCUSSION
Tracheobronchomalacia (TBM) is characterized by
partial or complete disruption of the integrity of the
tracheal cartilage and occurs with an incidence of
approximately 1 in 2100 to 1 in 2200 births. Congenital
TBM accounts for 5
–
23% of all cases born with
pneumonia, and it is detected in about 50% of autopsy
examinations. This condition reflects not a loss of
tracheal integrity per se, but rather developmental
insufficiency and deformation of the anatomical layers
of the tracheal wall. The incidence is significantly higher
in males (82%) compared to females (18%), suggesting
that TBM may serve as a predisposing factor for the
development of chronic obstructive pulmonary disease
(COPD) later in life.
Infants born with tracheomalacia often exhibit fewer
severe clinicopathological manifestations, which can
result in underdiagnosis of the disease. This
underdiagnosis increases the risk of various forms of
COPD development in the future and aggravates the
severity of respiratory infections.
Based on etiology, TBM is classified into two types:
congenital and acquired. There is an ontogenetic
relationship between these types, with the acquired
form also resulting from developmental dysplasia of
the tracheobronchial wall during the intrauterine
period. Morphologically, TBM can be classified into
semicircular, crescent-shaped, and concentric types. All
forms manifest as a deficiency of components within
the anatomical layers of the tracheobronchial wall.
In semicircular and crescent-shaped tracheomalacia,
the mucosal layer remains intact, while the main defect
is observed in the connective tissue. Specifically, there
is a numerical reduction of chondrocytes and failure of
the cartilage wall to occupy approximately three-
quarters of its normal structure. Small clefts are
observed, accompanied by deformation due to
contraction of the bronchial muscular bundles.
In crescent-shaped tracheobronchomalacia, the
connective tissue within the bronchial wall shows a
deficiency of chondrocytes, a sparse fibrous
extracellular matrix, and the presence of coarse fibrous
connective tissue around the periphery of the cartilage.
Additionally, glandular structures are underdeveloped.
These changes result in a marked reduction of the
morphofunctional
parameters
of
the
ciliated
epithelium lining the bronchial mucosa and cause
distortion of the annular relief on the inner surface of
the trachea and bronchi. Consequently, mucociliary
clearance is disrupted, leading to asphyxia and
aspiration syndromes.
Pathomorphological investigations detect these
pathological changes in only 23
–
47% of cases. In most
patients, areas of tracheal wall deformation flatten
after death, which often leads to failure in diagnosing
the cause of death (see Figure 1).
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Figure 1. Perisclerosis and fibromatosis of the connective tissue in the bronchial wall in
tracheobronchomalacia (1). Various degrees of morphological maturity of chondrocytes within the connective
tissue (2). Irregular clustering of chondrocytes (3). Interstitial edema is preserved in the peribronchial area.
Staining: Hematoxylin and Eosin (H&E). Magnification: 20x10.
In semilunar tracheobronchomalacia, the primary
features manifest as symmetrical developmental
dysplasia of the bronchial wall. One of the main
characteristics is the underdevelopment of the
connective tissue on either the right or left wing of the
tracheobronchial wall, which leads to adhesion of the
mucous membranes to each other, resulting in friction
and erosive lesions on their surfaces. These changes
clinically present as aspiration syndrome.
The dysplastic connective tissue contains chondrocytes
that are smaller in size, with immature small-nucleated
cells still in development. The stroma is filled with a
homogeneous interstitial substance, and at the
periphery, there is delayed development of the muscle
layer and bronchial glands.
In areas of the bronchial wall lacking connective tissue,
muscle bundles undergoing myosclerosis are observed.
The mucous membrane is incompletely formed, and
the epithelial lining on the mucosal surface shows
metaplastic changes, characterized by cuboidal and
semi-flattened covering epithelium with a marked
reduction in cilia (see Figure 2).
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International Journal of Medical Sciences And Clinical Research (ISSN: 2771-2265)
Figure 2. In tracheobronchomalacia, immature chondro-fibromatous and sclerotic connective tissue with
morphological signs of dysplasia is observed (1). Bronchial glands exhibit various forms of hypersecretion with
areas of calcification (2). There is an increase of sparse and coarse fiber connective tissue in the interstitium,
with regions of interstitial edema undergoing organization (3). Staining: Hematoxylin and Eosin (H&E).
Magnification: 40x10
This is manifested by the formation of interstitial
edema beneath the mucosal layer and the appearance
of irregular vascular fullness in the blood vessels.
In the concentric form of tracheobronchomalacia,
developmental delay or aplasia is observed across all
anatomical layers of the bronchial wall. Foci of
multilayered squamous epithelium persist on the
mucosal surface, with some elements resembling the
esophageal tissue wall. Chondrocytes within the
connective tissue are diffusely small in shape, and
metachromasia
is
observed
in
the
mucopolysaccharides of the extracellular matrix in the
interstitial spaces (see Figure 3).
Figure 3. Areas of developing chondro-fibromatosis and sclerosis with morphological signs of dysplasia in the
connective tissue are identified (1); hypersecretion of bronchial glands in various forms, with foci of
calcification present (2); increased loose and dense fibrous connective tissue in the stroma, with regions of
organized interstitial edema observed (3).
Staining: Hematoxylin and Eosin (H&E). Magnification: 20x10.
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This, in turn, confirms that the thickening of the
bronchial wall, along with the irregular and chaotic
formation of fibrous tissue components around the
connective tissue, leads to adhesions between the
muscular layer and the basal membrane of the
perimysial fascicular membrane. This process results in
various forms of muscle bundle atrophy and a
reduction in their morphofunctional characteristics.
Consequently, it contributes to the macroscopic
formation of deformed bronchi. The increase of loose
and dense fibrous connective tissue around the
perimeter of the connective tissue ring leads to the
development of interstitial edema and deformities (see
Figure 3).
Figure 4. In tracheobronchomalacia, glands exhibit varying degrees of morphofunctional development (1).
Interstitial edema and focal inflammatory infiltrates are observed around the glandular perimeter (2). In the
interstitial space, mucoid degeneration of loose and dense fibrous connective tissue and accumulation of
homogeneous mucus substances are detected (3).
Staining: Hematoxylin and Eosin (H&E). Magnification: 40x10.
Primarily, in areas where the connective tissue of the
cartilage is underdeveloped and merges with fibrous
connective tissue, foci of hypercellular tissue with small
basophilic inclusions and hyperchromatic cells
—
remnants from the embryonic period
—
are identified,
confirming morphofunctional hypoactivity.
Clinically and morphologically, this manifests as
incomplete bronchial dilation, a predisposition to
bronchospasm, friction between mucosal layers, and
stimulation of asphyxia processes. Consequently, in
neonates born during the early neonatal period, this
leads to the development of asphyxia and aspiration
syndrome, along with impaired mucociliary function of
the bronchi.
It
is
noteworthy
that
macroscopically
in
tracheobronchomalacia, bronchial lumen narrowing by
one-third, stenosis to half, and contraction to five-
fourths of the normal diameter are observed. In our
study, nearly 46.6% of examined
tracheobronchomalacia
cases
showed
lumen
narrowing to half, 31.3% to one-third, and 22.1% to
five-fourths of the normal bronchial diameter. Directly
related to asphyxia, 68.7% of these cases resulted in
death.
The above findings in tracheobronchomalacia are
characterized by delayed development of bronchial
cartilage, muscle, and mucosal layers during intra- and
postnatal ontogenesis, presence of focal chronic
inflammatory lesions, abundant loose and dense
fibrous connective tissue surrounding cartilage plates,
areas of chondro-fibromatosis, and hypercellular foci
with embryonic small cells.
Clinically and morphologically, this suggests a high
likelihood of aspiration syndrome during the
postoperative rehabilitation period following palliative
surgical interventions, emphasizing the importance of
relying on morphological criteria for treatment
planning.
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International Journal of Medical Sciences And Clinical Research (ISSN: 2771-2265)
CONCLUSION
Tracheobronchomalacia (TBM) represents a significant
pathological condition characterized by the partial or
complete loss of structural integrity of the tracheal and
bronchial walls, resulting in airway collapse. Its
prevalence, as evidenced by epidemiological data,
ranges approximately from 1:2100 to 1:2200, with
congenital forms accounting for 5
–
23% of neonatal
pneumonia cases and being identified in up to 50% of
pathological autopsies. This underscores the frequent
underdiagnosis of the condition during life, often due
to its subtle clinical manifestations and morphological
variability.
The pathogenesis of TBM is multifactorial, involving
both congenital and acquired etiologies. Congenital
TBM arises from developmental dysplasia of the
connective tissue and cartilage components of the
airway wall, often leading to incomplete maturation of
chondrocytes and aberrant formation of the
tracheobronchial framework. Acquired forms are
linked ontogenetically to prenatal insults and postnatal
inflammatory or mechanical injuries. Morphologically,
TBM manifests in several distinct patterns
—
including
semilunar, crescentic, and concentric types
—
each
defined by specific histological changes such as
hypoplasia or aplasia of cartilage, peribronchial
fibrosis, and muscular atrophy.
Histopathological examination reveals a spectrum of
alterations: from immature chondro-fibromatous
tissue with varying degrees of fibrosis and sclerosis, to
irregular clustering and depletion of chondrocytes
within the connective tissue matrix. These changes are
frequently
accompanied
by
hyperplasia
and
hypersecretion of bronchial glands, mucosal epithelial
metaplasia, and marked reduction in ciliary function,
contributing to impaired mucociliary clearance and
predisposing patients to recurrent infections,
aspiration syndromes, and potentially fatal asphyxia.
The thickening of the bronchial wall observed
macroscopically results from disorganized fibrotic
remodeling of connective tissue, which disrupts the
normal architecture and induces muscular layer
atrophy and functional decline. This fibrosis,
particularly around the perimucosal regions, leads to
airway stenosis and deformation. These pathological
features contribute to the clinical picture of airway
obstruction, chronic inflammation, and respiratory
insufficiency frequently observed in affected neonates
and infants.
Moreover, our findings highlight the significant
association between TBM and obstructive pulmonary
disease development later in life, notably chronic
obstructive pulmonary disease (COPD), especially in
male patients where incidence reaches up to 82%. The
high prevalence of bronchial narrowing
—
documented
as a reduction in lumen diameter to one-half or less in
nearly half of cases
—
correlates strongly with increased
mortality due to asphyxia and respiratory failure.
Given these complex morphofunctional changes, early
recognition and accurate morphological assessment of
TBM are imperative for guiding clinical management.
The persistent hypoplasia and dysplastic changes of the
connective tissue, muscular, and mucosal layers
underscore the necessity of tailored therapeutic
approaches. These may include palliation, surgical
intervention, and vigilant post-operative care to
mitigate aspiration risk and improve respiratory
function.
In summary, tracheobronchomalacia represents a
multifaceted developmental and acquired disorder of
the airway, where pathological remodeling and
structural deficits lead to significant morbidity and
mortality in neonatal and pediatric populations.
Detailed morphopathological evaluation remains
essential for diagnosis, prognosis, and optimizing
therapeutic strategies to improve patient outcomes.
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