Introduction

Lower respiratory tract malformations are rarely reported anomalies in adults.1 They are more commonly observed as a cause of early respiratory distress in newborns.1 Bronchogenic cysts, in particular, are rarely discovered in adults.1 Bronchogenic cysts result from abnormal budding of the foregut during development.1 The clinical presentation in adults varies and includes recurrent cough, wheezing, and pneumonia; some clinical features may mimic that of asthma.1 Historically, the traditional approach for diagnosis involves surgical resection with gross pathologic and histopathologic analysis; however, several radiographic features may suggest the diagnosis.2 On computed tomography (CT), bronchogenic cysts may be round, well-circumscribed, well-marginated lesions of varying size that generally attenuate at the level of simple fluid.2 The presence of proteinaceous material, hemorrhagic material, or cartilage can increase the attenuation on CT.2 Location varies, but most bronchogenic cysts are located within the mediastinum or the pulmonary parenchyma.2

Definitive diagnosis and management traditionally require surgical resection for pathologic analysis.1,2 The role of bronchoscopy with endobronchial ultrasound (EBUS) and transbronchial needle aspiration (TBNA) for diagnosis and management of bronchogenic cysts is not well understood. There are case reports documenting the use of EBUS-TBNA for aspiration of fluid from suspected mediastinal cysts.3–5 However, since bronchoscopy is not a sterile procedure, there is concern among clinicians regarding the risk of cyst rupture and infection, specifically pneumonia and mediastinitis. Herein, we report a case of an incidentally discovered mediastinal mass that was successfully determined to be a bronchogenic cyst with the use of bronchoscopy with EBUS-TBNA.

Case Presentation

A 57-year-old woman with a past medical history of obesity, hypertension, prior tobacco abuse (20 pack-year), type 2 diabetes mellitus, and schizophrenia was referred to the pulmonary office for abnormal imaging. The patient initially had a CT chest, abdomen, and pelvis with intravenous (IV) contrast performed in the emergency room to evaluate for nausea and vomiting. This revealed a 3.0 by 2.5 cm round, right-sided, paratracheal lesion that attenuated at average 12 Hounsfield units (HU). She reported no respiratory symptoms at that time. She was referred to pulmonary for further evaluation; however, she was lost to follow-up. Over 6 months later, she underwent repeat CT chest with IV contrast, which revealed the lesion increased in size to 3.6 x 2.7 cm (Figure 1). The lesion, again, attenuated at the level of simple fluid. Additionally, the scan showed a new pericardial lesion measuring 3.0 x 1.9 cm (Figure 2). This lesion was also round, well-marginated, and attenuated at average 30 HU. The patient was still asymptomatic, and she reported no personal or family history of malignancy.

Figure 1
Figure 1.CT chest with axial (A) and coronal (B) slices showed a round, homogenous, well-circumscribed lesion within the right paratracheal region (red arrow).
Figure 2
Figure 2.CT chest with axial (A) and coronal (B) slices showing second, smaller, homogenous lesion abutting the right upper pericardial space (red arrow).

The patient underwent bronchoscopy with EBUS. Basic airway exam revealed no significant abnormality. After introducing the linear EBUS into the trachea, the scope was rotated clockwise 45 degrees and flexed upward, which revealed a large anechoic lesion within the suspected region based on imaging (Figure 3). The lesion displayed no obvious internal septations or color Doppler signal (Figure 4). An Olympus 22-guage ViziShot TBNA needle was used for fine needle aspiration (FNA) of the lesion under direct ultrasound guidance (Figure 5). With the utilization of suction, more than 30 cc of serous fluid was aspirated from the lesion, and no purulence was noted (Figure 6). Repeat EBUS showed the cyst clearly decreased in size after aspiration of fluid. Cytological analysis of the fluid revealed no malignant cells. Cell count revealed 161 nucleated cells with a lymphocyte predominance (67%). Additional fluid studies revealed a lactate dehydrogenase (LDH) level less than 100 U/L, total protein 3.5 g/dL, and glucose 111 mg/dL. The patient tolerated the procedure well with no immediate complications. Based on the radiographic and transudative nature of the fluid, it was determined with relative certainty that the mediastinal lesion was a bronchogenic cyst. It was also assumed that the pericardial lesion was a pericardial cyst. Outpatient follow-up was arranged with plans for future imaging to monitor for progression.

Figure 3
Figure 3.EBUS showing the corresponding anechoic lesion in the right paratracheal space, measuring at least 3 cm.
Figure 4
Figure 4.EBUS of the same anechoic lesion with obvious lack of color Doppler signal.
Figure 5
Figure 5.FNA of the cystic lesion with resultant decrease in size.
Figure 6
Figure 6.Gross image of serous fluid obtained during real-time aspiration.

Discussion

The differential diagnosis for a mediastinal mass is broad.1 Cystic lesions, however, narrow the differential. Based on radiographic appearance and location, clinicians should consider bronchogenic cyst as a possibility when evaluating a mediastinal lesion that attenuates at the level of simple fluid. Patients with bronchogenic cysts may be asymptomatic, and the lesion is often identified incidentally in adulthood.1 Controversy exists with regards to diagnosis and management. Although no formal guidelines exist, surgical excision is considered the standard approach when the bronchogenic cyst results in clinically relevant symptoms.2 Some clinicians may offer radiographic follow-up when patients are asymptomatic. However, if surgery is delayed, the cyst may increase in size and potentially adhere to surrounding structures, which is associated with poorer surgical outcomes.6 Furthermore, there is a risk of malignant transformation after bronchogenic cysts become symptomatic.3 The added benefit of surgical resection is definitive pathological analysis.3,6 Few case reports have been published detailing the use of intermittent EBUS-TBNA for both diagnosis and management of bronchogenic cysts, specifically in patients with minimal symptoms or those who are deemed poor surgical candidates.

A case series published by Jaber and colleagues in 2014 evaluated the use of EBUS-TBNA in the diagnosis and management of 14 patients diagnosed with bronchogenic cysts over a 5-year period. Interestingly, the bronchogenic cysts were most commonly located in the right paratracheal region (in 9 out of 14 patients). The average cyst size was 4.6 cm, and the average amount of fluid aspirated with EBUS-TBNA was 54 cc. Five patients remained asymptomatic on follow-up and did not require surgical resection. Four patients had continual symptoms and eventually required surgical resection. Five patients were lost to follow-up. Only one patient was reported to have an adverse outcome, which was inflammatory pericarditis. Overall, EBUS-TBNA was diagnostic in all 14 patients and therapeutic in more than one-third of the patients.

A report on 2 cases published by Twehues and colleagues in 2011 described the use of EBUS-TBNA in 1 case to diagnose and manage a bronchogenic cyst incidentally discovered in a 37-year-old woman. The patient was found to have a large, 4.0 x 5.6 cm, right paratracheal mass with no prior imaging for comparison. The patient was reluctant to have surgery, so she underwent bronchoscopy with EBUS-TBNA; a 22-guage needle was used to aspirate more than 150 cc of straw-colored fluid from the lesion. Fluid analysis was unremarkable, and post-procedure imaging showed a reduction in the size of the lesion. Repeat CT over 16 months later showed continued complete resolution of the cystic mass, and the patient remained asymptomatic. The same authors described a separate case of a failed attempt at aspiration via EBUS-TBNA of an intrapulmonary cyst due to significant internal septations.

The few case reports described above suggest EBUS-TBNA may be a relatively safe method of diagnosing and potentially treating a bronchogenic cyst. However, more data regarding long-term follow-up and potential complications are needed. A case report by Hong and colleagues published in 2013 described the use of EBUS-TBNA to diagnose a 6.9-cm, well-marginated, homogenous bronchogenic cyst located posterior to the bronchus intermedius. Serous fluid was aspirated using a 22-guage needle. Lab studies, including cytology and microbiology, were unremarkable. One week later, the patient presented with fever, cough, and sputum production. Repeat imaging showed evidence of cyst rupture and the development of a cavitary pneumonia in the same region. She received three weeks of amoxicillin-clavulanic acid with both clinical and radiographic improvement.

A case report by Onuki and colleagues published in 2014 described the use of EBUS-TBNA to diagnose a 2.6 x 1.6 cm cystic lesion within the anterior mediastinum. A 22-guage needle was used to obtain minimal fluid that was “white and viscous.” Culture from the fluid grew α-hemolytic streptococcus, and the patient was prescribed oral antibiotics. Despite this, the patient returned 5 days later with fever and neck pain. Repeat imaging showed evidence of acute mediastinitis. She was treated with broad spectrum antibiotics and human immunoglobulin and was discharged in stable condition 13 days later. She underwent surgical excision of the lesion 5 months later, and final pathology confirmed a bronchogenic cyst. The characteristics and outcomes of these 4 patients can be seen in Table 1.

Table 1.Characteristics and outcomes of patients diagnosed with bronchogenic cyst by bronchoscopy with EBUS-TBNA.
Twehues and Islam (2011) Twehues and Islam (2011) Hong et al (2013) Onuki et al (2014)
Age 37 54 54 56
Gender Female Female Female Female
Symptoms Chest pain, cough Chest pain, cough Asymptomatic Asymptomatic
Imaging Characteristics 5.6 x 4 cm right paratracheal mass 5.7 x 4.3 cm left lower lobe intrapulmonary lesion with internal septations 6.9 cm well-defined, homogeneous, non-enhancing mass posterior to bronchus intermedius 2.6 x 1.6 cm cyst-like lesion in anterior mediastinum
Biopsy Needle Size 22-guage 22-guage 22-guage 22-guage
Fluid Characteristics Straw-colored, no growth on culture, no malignant cells Straw-colored, no growth on culture, no malignant cells Serous, no growth on culture, no malignant cells White, viscous fluid, no malignant cells, culture grew α-hemolytic streptococcus
Adverse Events None None Cavitary pneumonia in right upper lobe Mediastinitis
Ultimately Required Surgery for Definitive Management No Yes No Yes

The exact incidence of infectious complications following EBUS-TBNA of bronchogenic cysts is not well described in the literature. Although EBUS-TBNA is generally considered a safe and minimally invasive procedure, it is not a completely sterile procedure, which means there is always a risk of infection.4 This may be a result of cross-contamination as the biopsy needle passes through the bronchoscope’s working channel.4 This can potentially result in transfer of microorganisms into the mediastinal cyst when passing the FNA needle through the working channel.4 Furthermore, manipulation of the cyst can potentially result in cyst rupture and spillage of infected contents into the mediastinal space.5 Resultant infections can range from mild cases of pneumonia to potentially life-threatening cases of mediastinitis.4,5

Conclusion

Bronchogenic cysts are rare anomalies of development that can potentially result in non-specific respiratory symptoms.1 Although imaging may suggest the diagnosis, definitive diagnosis and management is usually acquired with surgical resection and pathologic examination.1,2 Bronchoscopy with EBUS-TBNA can be considered for real-time aspiration of cystic lesions, which can assist both in diagnosis and management.3,6 However, clinicians should be cautious, as significant complications have been reported with this method. Although the risk of infection and recurrence may potentially preclude use of EBUS-TBNA in managing bronchogenic cysts, it may be a reasonable alternative for patients who are unable or unwilling to undergo surgery.


Contributor Roles

M Assaad – data curation, investigation, writing original draft

R Meenakshisundaram – data curation, investigation, writing original draft

M Swalih – data curation

J Lantry – investigation

J Burgei – data curation

K Alsheimer – investigation

A Aqeel – review and editing

L Dubois – supervising

B Hehn – supervising

Funding Sources

The authors have no funding sources to report.

Patient details have been de-identified. Therefore, consent for publication by the patient was not required.

Disclosure of Interest

The authors declare they have no competing interests.