대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Infected Bronchogenic Cyst

Radiologic Findings

Chest radiograph obtained on emergency room shows a large mass in left upper lung zone showing broad attachment to the mediastinum. Contrast-enhanced CT scans show a well-defined cystic mass in left upper hemithorax with a beak-like connection to the mediastinum (on scan at the level of left main pulmonary artery) and enhancing rim-like consolidation of the surrounding lung. Also noted is left pleural effusion.
Operation revealed a cystic mass in the mediastinum. On gross examination, the cyst contained yellowish-brown necrotic material. Histopathologic examination demonstrated infected bronchogenic cyst with surrounding pneumonia.

Brief Review

Bronchogenic cysts result from defective growth of the lung bud. They are lined by ciliated epithelium and have focal areas of hyaline cartilage, smooth muscle, and bronchial glands within their walls. Two types have been described; mediastinal and intrapulmonary. Mediastinal cysts are far more frequently do not communicate with the bronchial tree, unlike intraparenchymal cysts in which such communications usually develop, leading to frequent recurrent infection.
The cysts occur most commonly within 2cm of the carina (subcarinal; right paratracheal) but can occur anywhere in the mediastinum. They contain mucoid material of variable viscosity that causes CT attenuation to vary from that of water to soft tissue. At MR, high-signal intensity is seen characteristically within cysts on T2-weighted image although variable signal intensities with different proportions of protein and/or hemorrhage in the cysts are observed on T1-weighted image.
Although most are thought to be asymptomatic and free of complications, many patients with bronchogenic cysts are symptomatic -due to compression of adjacent structures including the trachea and carina, mediastinal vessels, and even the left atrium- or have complicated cysts at the time of operation. The complications consist of fistula formation with the bronchial tree, ulceration of the cyst wall, hemorrhage, infection and rarely secondary bronchial atresia

References

1. Mediastinum. In Naidich DP, Zerhouni EA, Siegelman SS. Computed tomography and magnetic resonance of the thorax. 2nd ed. New York: Raven press. 1991: 35-148
2. Georges R, Deslauriers J, Duranceau A, Vaillancourt R, Deschamps C, Beauchamp G, Page A, Brisson J. Clinical spectrum of bronchogenic cysts of the mediastinum and lung in the adult. Ann Thorac Surg 1991 Jul;52 6-13
3. Nunzio MC, Evans AJ. Case report: the computed tomographic features of mediastinal bronchogenic cyst rupture into the bronchial tree. Br J Radiol 1994 Jun;67: 589-90

Keywords

Mediastinum, Congenital, infection,