Infected Bronchogenic Cyst With Left Atrial, Pulmonary Artery, and Esophageal Compression

Bronchogenic cyst is a rare foregut malformation that typically presents during the second decade of life that arises due to aberrant development from the tracheobronchial tree.¹ Mediastinal bronchogenic cyst is the most common primary cystic lesion of the mediastinum, and bronchogenic cysts of the mediastinum represent 18% of all primary mediastinal malformations.² Patients with mediastinal bronchogenic cysts may present with symptoms of cough, dyspnea, or wheezing if there is encroachment on surrounding structures.

Rarely, bronchogenic cysts can become infected. Definitive treatment of bronchogenic cysts is surgical excision; however, endobronchial ultrasound (EBUS)-guided drainage also can be employed. EBUS-guided drainage may be used when the cyst cannot be distinguished from solid mass on computed tomography (CT) images, to relieve symptomatic compression of surrounding structures, or to provide a histologic or microbial diagnosis in cases where surgical excision is not immediately available. We present the first-ever described case of bronchogenic cyst infected with Actinomyces, diagnosed by EBUS-guided drainage as well as a review of the literature regarding infected bronchogenic cysts and management of cysts affecting mediastinal structures.

Case Presentation

A 57-year-old African American male presented with a 4-day history of continuous, sharp, substernal chest pain accompanied by dyspnea. Additionally, the patient reported progressive dysphagia to solids. The posteroanterior view of a chest X-ray showed a widened mediastinum with splaying of the carina. A contrast-enhanced CT of the chest showed a large, middle mediastinal mass of heterogenous density measuring 7.3. × 7.0 × 6.0 cm with compression of the right pulmonary artery, left atria, superior vena cava and esophagus (Figure 1).

The mass demonstrated neither clear fluid-fluid level nor rounded structure with a distinct wall and uniform attenuation consistent with pure cystic structure and, in fact, was concerning for malignant process, such as lymphoma. Due to the malignancy concern and the findings of significant compression of surrounding mediastinal structures, the decision was made to proceed with bronchoscopy and EBUS-guided transbronchial needle aspiration (EBUS-TBNA) to assist in diagnosis and potentially provide symptomatic relief.

Under general anesthesia a P160 Olympus bronchoscope was advanced into the tracheobronchial tree; bronchoscopy with airway inspection revealed splayed carina with obtuse angle but was otherwise unremarkable. Next, an EBUS P160 fiber optic Olympus bronchoscope was advanced; ultrasound demonstrated a cystic structure. The EBUS-TBNA of cystic structure yielded 20 mL of brown, purulent fluid with decompression bringing pulmonary artery in ultrasound field (Figure 2). Rapid on-site cytology was performed with no preliminary findings of malignancy. The fluid was then sent for cytology and microbiologic evaluation.

Following EBUS-guided aspiration, the patient reported significant improvement in chest pain, dyspnea, and dysphagia. A repeat chest CT demonstrated decrease in mass size to 5.9 × 5.5 × 4.6 cm with relief of the compression of the right pulmonary artery and decreased mass effect on the carina (Figure 3). Pathology ultimately demonstrated no evidence of malignancy but did demonstrate filamentous material with sulfur granules and anthracotic pigment suggestive of Actinomyces infection (Figure 4).

The patient was placed on amoxicillin/clavulanate 875 mg to 125 mg twice daily for 4 weeks based on antibiotic susceptibility testing to prevent progression to mediastinitis related to Actinomyces infection. The duration of therapy was extrapolated from treatment regimens described in case series of cervicofacial and abdominal Actinomyces infections.³ Thoracic surgery evaluation for definitive excision of cyst was recommended after the patient completed his course of antibiotics.

The patient underwent dental evaluation to identify the source of Actinomyces infection but there appeared to be no odontogenic source. The patient also had extensive skin survey with no findings of overt source of Actinomyces and CT abdomen/pelvis also identified no abscess that could be a potential source. He subsequently underwent thoracoscopic resection with pathology demonstrating a fibrous cyst wall lined with ciliated columnar epithelium consistent with diagnosis of bronchogenic cyst (Figure 5).