대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Bronchogenic Cyst

Radiologic Findings

Posteroanterior and lateral chest radiographs show about 4 cm sized mass at posteriosuperior aspect of the left main bronchus. CT scan shows round homogenous low density mass located at posterior aspect of left main pulmonary artery. The mass is slightly indented by left main pulmonary artery. The mass is not enhanced at all after administration of contrast media.
Pathologic examination for the excised wall of the cystic mass revealed bronchogenic cyst.

Brief Review

Bronchogenic cysts are congenital lesions thought to result from abnormal budding of the embryonic foregut that occurs between the 26th and 40th days of gestation (1). Bronchogenic cysts are sometimes found in association with other congenital pulmonary malformation such as sequestration and lobar emphysema (2). Most bronchogenic cysts occurred in a characteristic location such as the subcarinal or paratracheal region. Less commonly, cysts may occur within the lung parenchyma, pleura, or diaphragm.
At computed tomography, bronchogenic cysts typically manifest as a spherical masses of either water or soft tissue attenuation. Findings on MR images parallel those on CT scans, and may include cystic components mixed with other tissue types. MR images of bronchogenic cysts have been reported to show signal similar to that of muscle on T1-weighted images, with a hyperintense to CSF on T2-weighted images. This finding suggests that mucus and proteinaceous debries within the cyst is the most likely explanation for the increased attenuation seen on CT scans (3).
McAdams et al. reported that following imaging features maybe helpful for differentiating non-water attenuation bronchogenic cysts from solid masses (4). First, the presence of a well-defined, thin, smooth wall suggests that the lesion is a cyst. Second, bronchogenic cysts with high CT attenuation numbers are usually of homogeneous attenuation and have cyst contents that do not enhance following administration of contrast material. Third, MR imaging can be very useful for differentiating high-attenuating cysts on CT scans from soft-tissue mass. Such cysts are typically isointense or hyperintense to CSF with all pulse sequences.

References

1. Chapman KR, Rebuck AS. Spontaneous disappearance of a chronic mediastinal mass. Chest 1985; 517-518
2. Heitzman ER. The lung: radiologic-pathologic correlation. Vol 1. St Louis, Mo:Mosby, 1984;17-38.
3. Lyon RD, McAdams HP. Mediastinal bronchogenic cyst: Demonstration of a fluid-fluid level at MR imaging. Radiology 1993;186:427-428.
4. McAdams HP, Kirejczyk WM, Christenson MLRd, Matsumoto S. Bronchogenic cyst: Imaging features with clinical and histopathlogic correlation. Radiology 2000; 217:441-446.

Keywords

Mediastinum, Congenital,