Yonago Acta medica 2010;53:77–81

Thoracoscopic Resections of Bronchogenic Cysts Arisingin the Posterior Mediastinum: A Report on 3 Patients
Yasuaki Kubouchi, Hiroshige Nakamura*, Shinji Fujioka*, Ken Miwa*, Yuzo Takagi*,
Yohei Yurugi*, Tomohiro Haruki* and Yuji Taniguchi*
Post-Graduate Clinical Research Center and *Division of General Thoracic Surgery, Tottori University Hospital, Yonago 683-8504 Japan

We report 3 cases of patients with bronchogenic cyst arising in the posterior mediastinum.
The patients were a 19-year-old male, a 36-year-old female and a 33-year-old female,whose cysts were detected as abnormal shadows in the chest. In 2 of them, neurogenic
tumors were suspected preoperatively. We performed thoracoscopic resection for the 3 tumors. Bronchogenic cysts may occur ectopically, and the posterior mediastinum must be
sufficiently recognized as a rare but possible ectopic site.
Key words: bronchogenic cyst; posterior mediastinum; thoracoscopic surgery

Bronchogenic cysts are benign tumors that frequently occur in the middle mediastinum, but occasionally arise ectopically due to the abnormal
presence of the tracheal primordium (Di Lorenzoet al., 1989). We encountered 3 patients with relatively rare bronchogenic cysts of the posterior mediastinum, and treated them successfully by thoracoscopic resection.

10th thoracic vertebra, exhibiting iso-intensity on
T1-weighted imaging and high intensity on T2weighted imaging (Fig. 1b). Since these findings
suggested a cystically degenerated neurogenic
tumor as the most likely diagnosis, we performed
thoracoscopic surgery. A lobulated yellowish cystic mass was present on the left side of the vertebral body, which was completely resected (Fig. 1c).
Histopathologically, the cystic lesion was coveredby the pseudostratified ciliated columnar epithelium and stratified squamous epithelium with themucus glands in the cyst wall. We diagnosed thelesion as a bronchogenic cyst originating from theposterior mediastinum (Fig. 1d). The postoperative
course was uneventful.
Case 2 was a 36-year-old female patientalso with an abnormal chest shadow, which wasnoted during outpatient management for bronchialasthma. She was asymptomatic and the sound of
her respiration was normal. Blood tests presented
no abnormal findings. Chest X-ray examination
showed a massive shadow in the right hilar region.
By chest CT, a massive shadow of 40 mm in di-Patient Reports
Case 1 was a 19-year-old male patient with anabnormal chest shadow, which was detected on
mass screening. He was asymptomatic, and blood
tests were normal. On chest X-ray examination,a massive shadow was visible in the left inferiorlung field. Computed tomography (CT) of thechest presented a clearly circumscribed massive
shadow of 35 × 20 mm on the left margin of thedescending aorta (Fig. 1a). By magnetic resonanceimaging (MRI) of the chest, a cystic lesion of 35
× 15 mm was seen adhering to the left side of theAbbreviations: CT, computed tomography; MRI, magnetic resonance imaging

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ameter with a smooth margin and clear border wasvisible on the right side of the posterior mediastinum (Fig. 2a). Chest MRI revealed a high-intensity
cystic lesion of 34 × 34 mm on the right side of the8th thoracic vertebra on both T1- and T2-weighted
imaging (Fig. 2b). Since these findings suggested
ectopic bronchogenic cyst, thoracoscopic surgery
was performed. Under thoracoscopy, the mass hada smooth and transparent surface through which
its interior could be observed, and was completely
resected (Fig. 2c). Histopathologically, the lesion
was a cyst covered by the pseudostratified ciliatedcolumnar epithelium with the cartilage and mucus
glands in the cyst wall. We made the diagnosisof bronchogenic cyst (Fig. 2d). The postoperative
course was uneventful.

aCase 3 was a 33-year-old female patient with
an abnormal chest shadow, which was detectedduring outpatient treatment for bronchial asthma.
The patient was asymptomatic, and blood tests
were normal. On chest X-ray examination, anabnormal shadow was present on the mediastinalside of the left upper lung field. Chest CT showeda low-density mass with a smooth margin and homogeneous interior of 15 × 7 mm on the left sideof the 4th thoracic vertebra (Fig. 3a). Chest MRI
revealed a cystic lesion of 29 × 14 mm, whichshowed iso-intensity on T1-weighted imaging andhigh intensity on T2-weighted imaging, on the left
side of the 4th thoracic vertebral body (Fig. 3b).
Since these findings suggested a cystically degenerated neurogenic tumor, thoracoscopic surgery wasbc
Fig. 1. Bronchogenic cyst in a 19-year-old asymptomatic male.

da: Chest contrast CT shows a clearly circumscribed tumor mass (arrow) in the left margin of the descending aorta.
b: On T2-weighted image, a high-intensity tumor (arrow) adheres on the left side of the 10th thoracic vertebra.
c: Intraoperatively, we observed a lobulated yellowish cystic mass attach to the vertebral body.
d: Pathologically, the resected tumor presents bronchogenic cyst lined by the pseudostratified ciliated columnar epithelium and stratified squamous epithelium with the mucus glands (hematoxylin and eosin staining). Bar = 100 µm.
CT, computed tomography.

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Bronchogenic cyst in posterior mediastinum

abcFig. 2. Bronchogenic cyst in a 36-year-old asymptomatic female.

da: By chest contrast CT, a clearly circumscribed tumor mass (arrow) is seen on the right side of the posterior mediastinum.
b: T2-weighted image shows a high-intensity tumor (arrow) on the right side of the 8th thoracic vertebra.
c: Intraoperatively, we observed a bronchogenic cyst with a transparent surface through which its interior was visible.
d: Pathologically, the resected tumor shows cyst lining of the pseudostratified columnar respiratory epithelium, withthe cartilage and mucus glands in the cyst wall (hematoxylin and eosin staining). Bar = 100 µm.
CT, computed tomography.

performed. On thoracoscopy, the mass was eggshaped, smooth-surfaced and pale yellowish, witha transparent surface through which the interior
could be observed. The mass was completely resected (Fig. 3c). Histopathologically, the it was a
cystic lesion covered by the pseudostratified ciliated columnar epithelium. Although no cartilage,smooth muscle or mucus gland was recognizedin the cyst wall, we judged the findings not to becontradictory to the diagnosis of bronchogenic cyst
arising from the posterior mediastinum (Fig. 3d).
The postoperative course was uneventful.

Discussion
Bronchogenic cysts occur congenitally due toabnormal budding or the ectopic presence of thetracheal primordium originating from the ventraloutgrowth of the foregut (Di Lorenzo et al., 1989).
They frequently appear outside the mediastinum or
pleura if there is growth due to abnormal budding
in an early stage of embryonic development, butin the lung if it occurs in a late stage (Maier et al.,1948). Bronchogenic cysts are classified primarily into intrapulmonary and mediastinal types (Ko79

Y. Kubouchi et al.

abcFig. 3. Bronchogenic cyst in a 33-year-old asymptomatic female.

da: By chest contrast CT, a clearly circumscribed and a low-density mass (arrow) is on the left side of the 4th thoracic
vertebra.
b: T2-weighted image shows a high-intensity tumor (arrow) on the left side of the 4th thoracic vertebral body.
c: Intraoperatively, we observed an egg-shaped and pale yellowish bronchogenic cyst with a transparent surface
through which its interior was visible.
d: Pathologically, the resected tumor is bronchogenic cyst lined by the pseudostratified ciliated columnar epithelium
although no cartilage, smooth muscle or mucus gland is recognized in the cyst wall (hematoxylin and eosin staining). Bar = 100 µm.
CT, computed tomography.

Bronchogenic cysts are usually asymptomatic
if they are of the intrapulmonary type. If they areof the mediastinal type, symptoms such as wheezing, coughing, dyspnea, atelectasis and dysphagia
appear due to bronchial compression. Also, severe
symptoms including bloody expectoration, bloody
sputum, hemoptysis, fever and pyothorax occur insome patients if the condition is complicated byinfection. Of the present 3 patients, 2 had a historyof asthma, but it was not related to the tumor, andboth were asymptomatic. This was probably because the cyst arose in the posterior mediastinum,
was small and had no accompanying infection.

et al., 2006), and the latter is further classified byMaier into types I (paratracheal), II (bronchial bifurcational), III (hilar), IV (paraesophageal) and V(others) (Maier et al., 1948). Types I, II and III arisein the middle mediastinum, types IV and V arise in
the posterior mediastinum, and type V also arisesin the anterior mediastinum. Lesions occurringin the middle mediastinum are the most frequent,
with those occurring in the posterior mediastinum
accounting for about 17% (McAdams et al., 2000).
Also, 84% of the patients with this disease showed
onset at the age of 40 years or below (McAdamset al., 2000), and all 3 patients presented here were
under 40.
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Bronchogenic cyst in posterior mediastinum

Differential diagnoses include neurogenictumors, Castleman lymphoma and pulmonary
sequestration. Generally, high-signal intensity on
T2-weighted MRI indicates cystic disease, but differentiating it from neurologic tumors, which may
also be cystic, is difficult. In fact, in previous repports bronchogenic cysts of the posterior mediastinum were preoperatively diagnosed in only 10 to
40% of the patients (Patel et al., 1994; Suen et al.,1993), and neurogenic tumors were also suspected
in 2 of our 3 patients initially.
Large size, rapid growth and being symptomatic have been considered surgical indications ofmediastinal bronchogenic cysts. However, there
have been reports of malignant transformation of
the cyst wall during the course of bronchogeniccysts (Ashizawa et al., 2001), developing into superior vena cava syndrome (Rammohan et al.,1975) or pulmonary artery embolism (Worsnopet al., 1995). Therefore, surgical treatment, particularly thoracoscopic surgery, is recommended
for this disease. It is also very significant for ourpresented cases of tumors arising in the posterior
mediastinum to be differentiated from neurogenic
tumors with cystic degeneration by performing
thoracoscopic resection. Thoracoscopic surgery
is not only less invasive than open chest surgery,but also less frequently causes complications suchas hemorrhage, cyst perforation and nerve injury,
and is esthetically more satisfactory. Other lessinvasive methods, for example, simple fine needle
aspiration or ethanol injection are inferior to surgical resection in radicality. Thoracoscopic surgeryof the posterior mediastinum requires caution to
avoid damaging structures such as the sympathetic
trunk, aorta, esophagus and thoracic duct, but provides a better view, and is easier in many respects,

than that of the middle or anterior mediastinum.
Bronchogenic cysts may occur ectopically, and thepossibility of their occurrence, although rare, in theposterior mediastinum must be sufficiently recognized, in which case, particular attention towarddifferentiation from neurogenic tumors is necessary.
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Received October 4, 2010; accepted October 28, 2010
Corresponding author: Hiroshige Nakamura, MD81