Bronchogenic Cyst

Bronchogenic Cyst

CR – Middle mediastinal mass; otherwise negative.

CT – Uniformly thin walled fluid attenuation right paratracheal mass.

Bronchogenic cysts result from abnormal ventral budding of the tracheobronchial tree during development. The walls of these lesion are of variable thickness and may contain cartilage, smooth muscle, and mucous gland tissue. Epithelial lining is secretory and consequently the cyst may contain proteinaceous and/or mucoid fluid. Bronchogenic cysts are occasionally found in association with other congenital pulmonary malformations such as sequestration and lobar emphysema. They may undergo an abrupt increase in size as a result of hemorrhage or infection. The majority are asymptomatic, but they may occasionally cause symptoms secondary to compression of adjacent structures. On conventional chest radiographs, a bronchogenic cyst usually appears as a well-defined solitary mass near the carina often toward the right. On CT scans, a bronchogenic cyst appears as a smooth, round or elliptic mass with an thin wall and uniform attenuation (HU vary depending upon fluid content). Air within the cyst is uncommon and suggestive of secondary infection and communication with the tracheobronchial tree. Calcification occurs occasionally in the wall or within the cyst contents. On MR, T1 signal varies with cyst contents but T2 signal is uniformly increased; fluid-fluid levels are sometimes evident.

Jeung MY, Gasser B, Gangi A, et al. Imaging of Cystic Masses of the Mediastinum. Radiographics (2002); 22: S79-S93.