Keywords
surgical treatment - tracheal lipoma - bronchoscopy - tracheal stent
Introduction
Primary tumors of the trachea account for less than 0.1% of tumors and most of them
are malignant.[1] As one type of benign tumors, primary tracheal lipoma is very uncommon. Because
of the characteristic of slow growth, patients with benign tracheal tumors develop
symptoms of airway obstruction gradually. Therefore, they are usually misdiagnosed
as asthma, chronic obstructive pulmonary disease, or bronchitis, and the definitive
diagnosis of these tumors is usually delayed.
We describe a case where lipoma was first misdiagnosed as bronchial asthma, followed
by sudden aggravation of dyspnea after trauma, and cervical, thoracic computed tomography
(CT) confirmed a tracheal tumor. Through multiple bronchoscopy interventions and placements
of a tracheal stent, little therapeutic benefit was discovered, and resection of the
tracheal tumor combined with tracheal end-to-end anastomosis was performed to ultimately
achieve a cure.
Case Presentation
A 35-year-old man has suffered from dry cough and shortness of breath recurrently
for 4 years, and those symptoms gradually worsened. During the past 6 months, the
patient developed exertional dyspnea after daily activities, accompanied by orthopnea.
Therefore, he went to a local hospital many times, and no abnormal sign was found
in the chest X-ray, and bronchial asthma was ultimately diagnosed. After treatment
with aminophylline, Bricanyl, and aerosol salbutamol, the symptom of dyspnea was alleviated,
while it relapsed frequently. After a traffic accident, the patient developed severe
dyspnea and could not maintain a supine position; therefore, he went to the local
hospital immediately. Physical examination: slight cyanosis of the lips, shortness of breath, obvious three-concave sign during
inhalation, skin abrasion on the front chest wall, no thoracic deformity, and wheezing
in both lungs, which was more obvious in the upper chest. Arterial blood gas analysis
showed a pH of 7.38, partial pressure of carbon dioxide of 46 mm Hg, and partial pressure
of oxygen of 54 mm Hg. Chest X-ray showed enhanced light transmission in both lungs
and no other abnormalities. CT and three-dimensional (3D) reconstruction of the neck
and chest found a soft tissue tumor located on both inside and outside the cavity
of the tracheal posterior wall. In addition, the intratracheal tumor was round, and
its upper margin was 2.1 cm away from the glottis. The length of the diseased trachea
was 3.9 cm. The corresponding tracheal cavity became narrow, and the pathological
change in the surrounding tissue outside the trachea and within its boundaries was
clear, without other abnormal findings; therefore, a tracheal tumor was considered
([Fig. 1A], [B]). The trauma experienced by this patient was not serious, and the corresponding
symptoms may have been caused by this tracheal tumor. Afterward, the patient was admitted
to the respiratory department.
Fig. 1 (A, B) CT showing an intratracheal tumor; (C) bronchoscopy showing a tumor on the
posterior wall of the trachea and a fissure-like stenosis between the tumor and tracheal
wall. CT, computed tomography.
Subsequently, the patient underwent fiberoptic bronchoscopy and interventional therapy.
The bronchoscopy showed that there was a tumor (∼1.5 cm below the glottis) on the
posterior wall of the trachea, which demonstrated an ∼2.3 × 2.3 cm hemispherical bulge
with smooth and soft surfaces; moreover, most of the tracheal cavity was occupied,
and a fissure-like stenosis was formed ([Fig. 1C]). An extended suction tube was placed into the distal end of the tumor to provide
oxygen. After the ventilation was improved, puncture biopsy was performed by using
a 14G needle, and then a high-frequency electrocoagulation encirclement was performed.
Afterward, a new organism (∼1.2 × 1.0 cm) was resected by a COOK AS-1 snare via high-frequency
electrocoagulation, and most of the tumor tissues were removed from inside the trachea;
then, a 2.0 × 5.0 cm tracheal stent was placed. The upper edge of the stent was located
∼1.5 cm below the glottis, and the lower edge was 7 cm away from the carina of the
trachea ([Fig. 2A]). After this operation, the symptom of dyspnea was significantly alleviated. One
week later, tracheal lipoma was confirmed by pathological examination. For this reason,
the tracheal stent was removed via bronchoscopy, and the residual tumor tissues were
removed as much as possible with the COOK AS-1 snare combined with high-frequency
electrocoagulation. The operation was performed successfully. As the tumor tissues
in the trachea were benign and resected very thoroughly, no tracheal stent was placed
at this time. However, previous symptoms appeared immediately after the operation.
After 6 days, the patient underwent bronchoscopy again. A 2.0 × 2.3 cm tumor (∼1.5
cm below the glottis) was found on the posterior wall of the trachea, whose surface
was rough ([Fig. 2B]). Therefore, an extratracheal tumor that had swelled into the trachea was considered
to lead to the above-mentioned symptoms. A 1.0 × 0.8 cm tumor was resected with the
COOK AS-1 snare, and the tracheal stent was placed again to improve the patient's
ventilation. After 4 days, chest CT showed complete patency of the stent ([Fig. 2C]).
Fig. 2 (A) Bronchoscopy showing a tracheal stent placed inside the tracheal cavity. (B)
Bronchoscopy showing an extratracheal tumor swelling into the trachea. (C) CT showing
a tracheal stent placed again and complete patency of the stent. CT, computed tomography.
After the consultation, this patient was transferred to our hospital, and surgery
was performed after placement of the tracheal stent for 10 days. After total intravenous
anesthesia and orotracheal intubation, the tube was placed underneath the tumor through
the tracheal stent. Using a collar-like transverse incision in the neck, under the
guidance and location of bronchoscopy, the cannula placed for tracheal intubation
was retracted below the glottis, and the position of the tumor was initially determined
according to the photic and opacity zones on the tracheal wall, whose accurate positions
were confirmed by puncture with a fine syringe needle. The trachea was cut off ∼0.5
cm below the tumorous lesion, and then the metal stent was removed; afterward, the
secretions inside the lower trachea and bronchus were removed as soon as possible,
and the sterile tracheal tube was inserted to ensure effective ventilation. Then,
the extratracheal pathological tissues were carefully dissociated to avoid damage
to surrounding tissues, such as the recurrent laryngeal nerve, blood vessels, and
the esophagus. The trachea was also cut off ∼0.5 cm above the tumorous lesion, and
the tumor tissue was completely removed. The length of the resected trachea was 4.9
cm, including seven tracheal rings ([Fig. 3A]). The specimen was sent for rapid biopsy, which reported a negative stump. Then,
interrupted sutures were adopted with 3–0 Prolene thread, and end-to-end anastomosis
of the trachea was performed. The cannula placed for tracheal intubation was removed
before tying knots. Afterward, the cannula for orotracheal intubation was placed underneath
the anastomotic stoma to continue respiratory support, and knots were tied under the
condition of tension to decrease anterior cervical flexion. Moreover, no air leaks
were found at the anastomotic stoma according to an air charging test. After that,
the subcutaneous layer and skin of the patient's underjaw and anterior chest, respectively,
were sutured with thick silk threads to maintain a position of anterior cervical flexion
after surgery. As soon as the patient was awake, the cannula placed for tracheal intubation
was removed, and he breathed naturally and smoothly. Tracheal lipoma was diagnosed
according to the postoperative pathological examination ([Fig. 3B]). The mandibular and anterior chest threads were removed 3 weeks after the surgery;
tracheal patency was confirmed by CT 3 months postoperatively, and no tumor was found
([Fig. 3C]). In addition, no previous symptoms, such as cough and dyspnea, appeared after the
surgery.
Fig. 3 (A) Macrography showing a resected tracheal tumor and rings. (B) Pathological examination
confirming a tracheal lipoma. (C) Postoperative CT showing tracheal patency and no
tumor. CT, computed tomography.
Discussion
The majority of adult primary tracheal tumors are malignant, and benign tumors are
rare.[2]
[3] Primary benign tumors of the trachea mainly include leiomyoma, papilloma, fibroma,
hemangioma, chondroma, and mixed tumors of the salivary gland,[4]
[5] while lipoma is very uncommon.
Benign tracheal tumors tend to grow slowly and are asymptomatic at early stages. Therefore,
they are difficult to be diagnosed during this period; moreover, such tumors are easily
misdiagnosed after symptoms appear. Symptoms of airway obstruction appear when the
degree of tracheal blockage increases to 50 to 75% or when the lumen diameter is less
than 8 mm.[1] Generally, it is difficult to find a lesion with conventional chest X-ray because
the trachea is covered by the mediastinum. Furthermore, due to the low morbidity of
this disease, bronchial antispasmodic drugs have certain effects; therefore, these
lesions are usually misdiagnosed as bronchial asthma or pulmonary infection. This
patient had a chronic history lasting for 4 years and had been misdiagnosed with bronchial
asthma during that time. Because of the trauma, the diagnosis was able to be made
through cervical, thoracic CT and 3D reconstruction. This case suggests that in patients
with dyspnea, which worsens gradually, the possibility of a tracheal tumor should
be considered, and timely examination, including cervical, thoracic CT and bronchoscopy,
can provide an accurate diagnosis. In fact, the physical sign of this disease is mainly
inspiratory dyspnea, and it is evidently different from expiratory dyspnea caused
by bronchial asthma and pulmonary infectious diseases. Careful physical examination
can be helpful for differential diagnosis.
In this case, this patient has suffered endobronchial interventions four times, and
a stent was implanted at the first and third times. That is because the respiratory
physician worried about the resection of the tumor was incomplete, and there could
be some of the residual tumors which may lead to a stenosis of the trachea. In addition,
we have described a puncture biopsy of the tumor during the first endobronchial intervention,
whereas it showed a negative result. Soon, most of the tumors have been resected and
the ultimate tracheal lipoma was reported by pathological examination. Thus, a fresh-frozen
examination of the tumor was not necessary during our final surgical treatment.
However, there are some limitations to the therapeutic process. As is known, various
interventional treatments via fiberoptic bronchoscopy should only be applied to narrow-based
benign tracheal tumors that originate from submucosal, nodular, or polypoid tissues
protruding into the tracheal lumen, where the base is connected to the tracheal wall
by a pedicle with irregular length and uneven thickness. Moreover, the placement of
a tracheal stent may lead to a secondary obstruction caused by the growth of the tracheal
tumor, such as tracheal secretions blocking the distal end of the stent, bleeding,
and infection; the placement of a stent can only alleviate the symptoms of airway
obstruction to some extent and cannot achieve a cure or prolong survival time in patients.
Thus, a stent is only used for patients without the opportunity for surgical therapy,
who are not suitable for surgical resection, or who seek relief from acute airway
obstruction as well as for saving rescue time.
In this patient, CT and 3D reconstruction of the neck and chest showed a soft tissue
tumor located on both inside and outside the cavity of the tracheal posterior wall.
Afterward, high-frequency electrocoagulation and placement of a tracheal stent were
first performed via bronchoscopy. After the symptom of dyspnea improved, surgery was
performed immediately, especially because pathological biopsy reported a benign tracheal
lipoma. Since then, multiple interventions with bronchoscopy and placements of a tracheal
stent have resulted in repeated respiratory symptoms repeatedly, increased patient
suffering and risk, and prolonged curative time.
In this case, the diameter of the tracheal wall invaded by this tumor was ∼70%, and
the length of the tracheal lesion was 3.9 cm. The boundary between the extratracheal
lesion and the surrounding tissue was distinct, and such lesions are resectable. The
preferred surgical procedure is sleeve resection and end-to-end anastomosis of the
trachea.
According to the preoperative findings from CT and bronchoscopy, as well as the pathological
data, we paid attention to the following points during the surgery. (1) As the tracheal
lesion was long, on the basis of complete resection of the tumor, the normal tracheal
ring was retained as much as possible to reduce the tension from anastomosis. The
extent of tumor invasion under the mucosa was wider than what we observed in the intracavity
of the trachea with the naked eye; although this patient had a benign lipoma, to achieve
the purpose of radical resection, the tracheal margin was made ∼0.5 cm away from the
upper and lower edges of the tumor. Therefore, under the guidance of bronchoscopy
during the operation, tracheal penetration with a syringe needle was used to determine,
as accurately as possible, the tracheal margin needed for resection. (2) Although
the resected trachea was long, to avoid excessive dissociation of the tracheal tissue,
which may impair the blood supply of the anastomosis, we considered whether it was
sufficient to dissociate the upper and lower ends of the trachea before achieving
anastomosis. (3) During dissociation of the extratracheal tumor, damage to the recurrent
laryngeal nerve, blood vessels, the esophagus, and other surrounding tissue should
be avoided. (4) To reduce anastomotic tension during the operation and postoperation,
knots were tied in anterior cervical flexion and the subcutaneous layer and skin of
the patient's underjaw and anterior chest, respectively, were sutured with thick silk
threads to maintain anterior cervical flexion after surgery. The threads were removed
3 weeks after surgery, and the back of the head was avoided for more than 3 months.
Conclusion
Primary tracheal tumors should be highly suspected in patients with recurrent and
gradually worsening dyspnea symptoms, including the three depressive signs of wheezing
in the neck, upper chest, and chest; timely cervical, thoracic CT and fiberoptic bronchoscopy
can provide an accurate diagnosis.
Various interventional treatments via fiberoptic bronchoscopy are mainly suitable
for benign tracheal tumors with narrow margins, and tracheal stent placement can only
alleviate the patient's symptoms of airway obstruction to some extent. Surgical radical
resection is the only way to cure all benign tracheal tumors.
If the circumference of the tracheal wall is mostly invaded by the tracheal tumor
and the length of the tracheal lesion is long, the preferred surgical procedure should
be sleeve resection and end-to-end anastomosis of the trachea.
