Bronchogenic cysts: a narrative review

Abstract

Background and objective: Bronchogenic cysts represent a rare form of cystic malformation of the respiratory tract. Primarily located in the mediastinum if occurring early in gestation as opposed to the thoracic cavity if arising later in development. However, they can arise from any site along the foregut. They exhibit a variety of clinical and radiologic presentations, representing a diagnostic challenge, especially in areas with endemic hydatid disease. Endoscopic drainage has emerged as a diagnostic and potentially therapeutic option but has been complicated by reports of infection. Surgical excision remains the standard of care allowing for symptomatic resolution and definitive diagnosis via pathologic examination; minimally invasive approaches such as robotic and thoracoscopic approaches aiding treatment. Following complete resection, prognosis is excellent with essentially no recurrence.

Methods: A review of the available electronic literature was performed from 1975 through 2022, using PubMed and Google Scholar, with an emphasis on more recent series. We included all retrospective series and case reports. A single author identified the studies, and all authors reviewed the selection until there was a consensus on which studies to include.

Key content and findings: The literature consisted of relatively small series, mixed between adult and pediatric patients, and the consensus remains that all symptomatic lesions should be excised via minimally invasive approach where feasible.

Conclusions: Surgical excision of symptomatic bronchogenic cysts remains the gold standard, with endoscopic drainage being reserved for diagnosis or as a temporizing measure in clinically unstable patients.

Keywords: Bronchogenic cyst; mediastinal cyst; mediastinum; robotic surgery.

Figure 1

Posterior mediastinal bronchogenic cyst. Subcarinal bronchogenic cyst detected by CT scan of chest with intravenous contrast to investigate complaints of mild dysphagia and nonspecific back pain in a 35-year-old healthy man. (A) Axial and coronal CT images demonstrates a smooth-bordered 4.5 cm cystic lesion in the subcarinal location. The cyst has high density with HU of 48 and thick proteinaceous fluid was drained at the time of robotic thoracoscopic resection. Red bordered arrow marks the cyst. (B) Coronal CT MRIs image delineates the bronchogenic cyst with the MRI image, T1-weighted image shows liquid nature of the cyst contents, demonstrating dark contents consistent with fluid. T2-weighted confirms these findings as illustrated by cyst bright finding. Complete resection was achieved by right robotic thoracoscopic approach, and the cyst was filled with thick proteinaceous fluid. Red bordered arrow marks the cyst. CT, computed tomography; HU, Houndsfield units; MRI, magnetic resonance imaging.

Figure 2

Anterior mediastinal bronchogenic cyst. (A) Incidental finding on cardiac CT scan for coronary artery calcium scoring in a 75-year-old asymptomatic woman. The cyst has low density with HU of 14 and clear fluid was found in the cyst at the time of robotic thoracoscopic resection. Red bordered arrow marks the cyst. (B) Incidental finding of anterior mediastinal cystic lesions by CT scan of the chest for investigation of non-specific chest discomfort in a 45-year-old woman. The cyst content had a high density with HU of 47 and proteinaceous fluid was drained that the time of robotic thoracoscopic resection. Red bordered arrow marks the cyst. CT, computed tomography; HU, Houndsfield units.

Figure 3

Intraparenchymal bronchogenic cyst. (A) Axial and sagittal images of a chest CT scan with intravenous contrast of a 34-year-old woman demonstrating a large peripherally located cyst in the right lower lobe, adjacent to segmental pulmonary vessels. She had a history an enlarging cystic lesion once complicated by an infection that was treated with a month-course of oral antibiotic. A complete resection was achieved by right robotic thoracoscopy and enucleation of the lung cyst separating the cyst wall from the underlying vessels and bronchus thus avoiding a pulmonary segmentectomy. Pathologic examination determined this lesion being a benign bronchogenic cyst. Red bordered arrow marks the cyst. (B) Axial and sagittal cuts of a CT scan with intravenous contrast of a 63-year-old woman admitted to the hospital with fever/chills and leukocytosis showing a cystic lesion in the right lower lobe with air-fluid level suggestive of an infected intrapulmonary bronchogenic cyst. This was her first presentation of a bronchogenic cyst. The cyst was completely resected by a right robotic thoracoscopy and wedge resection of the cyst. Final pathology report shows: Respiratory-lined cyst with fibrosis, adjacent fibrinopurulent exudate, granulation tissue and reactive mesothelial hyperplasia. Red bordered arrow marks the cyst. CT, computed tomography.

Figure 4

Histologic findings of bronchogenic cysts corresponding with imaging (hemoxylin & eosin stain). (A) Low power magnification (×12.5) reveals a thin-walled cyst with adjacent adipose and thymic tissue. (B) Higher power magnification (×400) demonstrates that the epithelial lining consists of ciliated pseudostratified columnar respiratory-type epithelium. The cyst wall lacks other features typical of a mature bronchogenic cyst. (C) Medium power magnification (×40) corresponding with images shown in Figure 2A,2B demonstrating an epithelial-lined cyst wall (upper lefthand corner) with adjacent seromucinous glands and mature hyaline cartilage (bottom righthand corner). (D) Higher power magnification (×200) demonstrates that the cyst wall is lined by an attenuated flat-to-cuboidal epithelium.