Imaging description

Bronchogenic cysts most commonly occur in the mediastinum with the majority seen in the region of the tracheal carina [1, 2]. They can also occur in the lung parenchyma, pleura, and diaphragm [2]. On CT, a mediastinal bronchogenic cyst most commonly presents as a homogeneous fluid attenuation mass with a thin or imperceptible wall (Figures 32.1 and 32.2) [1, 2]. The attenuation of the cyst is influenced by the contents of the cyst and if there is a high protein content or calcium oxalate in the fluid, the attenuation values can be soft tissue or calcium [3]. Air is typically not seen in mediastinal bronchogenic cysts unless they are infected. The contents of the cyst do not enhance with contrast (Figure 32.1), but the wall of the cyst may enhance. MRI can be helpful in cases where the cystic nature of the mass is not apparent on CT. Although the signal intensity of T1-weighted imaging can vary due to the content of the cystic fluid, the cystic nature of the mass is confirmed by the high signal intensity on T2-weighted images (Figure 32.3) [1, 2].

Importance

Bronchogenic cysts are benign lesions. If they are asymptomatic, no further workup or resection is required. Therefore, identification of the cystic nature of the mass is important to prevent more aggressive intervention.