Bronchogenic cyst with multiple complications
1 Fremantle Hospital, Fremantle, Australia
2 Department of General Medicine, Fremantle Hospital, Fremantle, Australia
Bronchogenic cysts are a rare type of mediastinal mass
thought to arise from abnormal budding of the embryologic foregut. This paper
presents a rare case of a 32-year-old male who developed multiple serious
complications from a bronchial cyst. This rare presentation is discussed and
the role of CT and MR imaging in making the diagnosis is highlighted. � 2007
Biomedical Imaging and Intervention Journal. All rights reserved.
Keywords: Bronchogenic cyst, atrial fibrillation, pleural effusion, pericardial effusion, computed tomography
Bronchogenic cysts are a rare cause of mediastinal mass
[1,2]. The embryologic foregut differentiates into oesophagus and trachea
during embryogenesis. Bronchogenic cysts occur along the differentiating
pathway of the trachea and bronchial tree, and are thought to represent
abnormal budding of foregut tissue. The thick walls of bronchogenic cysts may
contain columnar ciliated epithelium, cartilage and mucinous glands. They are
most often found in the mediastinum or lung, and sometimes in the neck .
Bronchogenic cysts are typically asymptomatic, with many detected incidentally.
However, complications do occur. Resection of even the asymptomatic cyst is
recommended because of the possibility of complications and the difficulty of operating
on complicated cysts [2,3].
An otherwise fit 32-year-old male presented with a dull
central chest pain, which gradually worsened over several days with associated
night sweats. Chest radiography (CXR) showed a mediastinal mass (Figure 1). CT
with contrast showed a 10 cm posterior mediastinal mass inferior to the carina
and adjacent to the left pleura, left atrium, pulmonary artery and oesophagus.
There was marked mass effect with left atrial and superior vena cava (SVC)
compression, right inferior pulmonary vein congestion and thrombus (Figure 2).
Clinical assessment did not reveal evidence of superior vena cava obstruction
or haemodynamic compromise. Given the history of sweats, and age of the
patient, a provisional working diagnosis of mediastinal lymphoma was made and
fine needle aspiration was pursued. Transthoracic echocardiography demonstrated
the mass as separate from the left atrium, however further comment on likely
diagnosis was not possible from the views obtained. Cardiac magnetic resonance
imaging (MRI) 48 hours after presentation showed a smooth walled structure not
communicating with the heart, oesophagus or bronchus, with the additional
development of pericardial and pleural effusions. High-dose dexamethasone was
commenced for treatment of presumed lymphoma until confirmatory tissue could be
obtained. The patient subsequently developed symptoms and ECG changes that was
consistent with pericarditis and runs of atrial fibrillation (AF). An
endoscopic transoesophageal ultrasound-guided fine needle aspirate (EUS-FNA)
was performed as the mass was considered too technically difficult to access by
percutaneous CT-guided FNA. The images at EUS-FNA showed a fluid-filled cyst
with hypoechoic particles (Figure 3). Frank pus was aspirated from the cyst. Streptococcus
salivarius and Streptococcus milleri was cultured from the aspirate
and a diagnosis of an infected cyst was made. Retrospective and detailed review
of all MR images yielded one sagittal view demonstrating a fluid level within
the cyst. (Figure 4) This had not been visible on CT or transthoracic
ultrasonography. IV amiodarone (for AF) and anticoagulation (for pulmonary vein
thrombus) was commenced and cardioversion occurred within 12 hours of
procedure. Steroids were ceased and IV ticarcillin and potasssium clavunate
(Timentin, GSK) was commenced. The patient was referred to Cardiothoracic
Surgeons for further management.
Upon thoracotomy the mass was identified, but could not be
removed because of its adherence to oesophagus, pericardium and pleura. It was
thus marsupialised into the oesophagus. A nearby enlarged mediastinal lymph
node was removed for histopathologic examination. Histopathology revealed a
reactive lymph node and material taken from the cyst wall displayed pseudostratified
ciliated respiratory type epithelium and glandular structures. No cartilaginous
material was seen in the excised section of the cyst wall. There was evidence
of inflammatory infiltrates in the sample. Post-operatively, the patient was
anti-coagulated (due to the pre-operative presence of thrombus on the CT) and
was discharged home once recovered 14 days after admission.
Serious complications from bronchogenic cysts are rare,
but can include SVC syndrome, tracheal compression, pneumothorax, pleurisy and
pneumonia . In a series of 68 paediatric and adult cases, 58% of patients
were symptomatic with pain (n=15), dyspnea (n=8), respiratory infection (n=7),
wheezing (n=5), cough (n=5), dysphagia (n=1), pneumothorax (n=1). The cyst
diameters in this study were 1.3 cm to 11 cm, with a mean of 4.8 cm . Atrial
fibrillation secondary to bronchogenic cyst has been previously described.
Electro-physiological studies in a patient with bronchogenic cyst and right
inferior pulmonary vein impingement showed atrial ectopic foci in the region of
the distended vein . Stretching of the pulmonary vein is known to lead to
abnormal firing of myocardiocytes. This was thought to produce atrial
fibrillation in the reported case . CT is commonly used in assessing
mediastinal masses. While the anatomy of the mediastinal mass is easily seen,
the modality is limited in its ability to diagnose bronchogenic cysts of high
density. The attenuation of the cyst�s contents can vary from that of water to
soft-tissue [5,7]. The value of attenuation can be as high as 100 Hounsfield
units if the cyst contains protein or calcium oxalate . In this case, the
combination of MRI, which revealed a fluid level and better defined the
anatomical relationships of the mass, together with transoesophageal
ultrasound, which characterised the internal structure of the mass and allowed
diagnostic aspirate, were critical to management.
Bronchogenic cyst of the mediastinum can present acutely
with several complications. In this case, the mass effect and the presence of
inflammation were likely related to the development of complications. The
multiple complications observed in this patient were: atrial fibrillation,
pericardial and pleural effusions, and pulmonary vein thrombosis. There was
also radiologic evidence of left atrial compression and SVC obstruction without
obvious significant clinical signs or symptoms. This case is of interest due to
the multiple complications and the diagnostic dilemma this case presented. The
diagnosis may be easily missed on CT and transthoracic ultrasound. MRI and
endoscopic transoesophageal ultrasonography were in this case helpful in
accurate characterisation of the mass.
Figure 1 CXR with splaying of the carina.
Figure 2 Computed tomography imaging of chest, with intravenous contrast showing superior vena cava compression (small arrow) and right inferior pulmonary vein compression and thrombus (large arrow).
Figure 3 Cardiac MRI with large cyst (arrow - internal fluid level)
Figure 4 Endoscopic transoesophageal ultrasound guided fine needle aspiration (arrow - hyperechoic particles within cyst)
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|Received 3 March 2007; received in revised form 14 August 2007; accepted 18 August 2007
Correspondence: Department of General Medicine, Fremantle Hospital, Alma Street, Fremantle WA 6160, Australia. Tel.: +619 9431 3333; E-mail: email@example.com (Nat P. Lenzo).
Please cite as: Marshall G, Cheah C, Lenzo NP,
Bronchogenic cyst with multiple complications, Biomed Imaging Interv J 2007; 3(4):e42
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