When the Chest Deceives the Heart: Mediastinal Bronchogenic Cyst Compressing the Left Atrium

Description of Clinical Presentation: A 39-year-old female patient presented complaining of progressive shortness of breath of 2 months duration associated with non-anginal central chest pain. The patient gave no significant past medical history. General examination was unremarkable except for a pulse rate of 110/min. Chest examination revealed bilateral fine basal crepitations while cardiac examination was remarkable for a pansystolic murmur heard maximally over the lower left sternal border which increases with inspiration and accentuated P2.





Diagnostic Techniques and Their Most Important Findings: Her initial workup included ECG that revealed sinus tachycardia. TTE revealed normal LV dimensions with preserved systolic function and dilated left atrium. The right ventricle was dilated but with preserved contractility. Moderate tricuspid incompetence was appreciated (EPASP = 70 mmHg) and high probability of significant pulmonary hypertension. The TTE was significant for two large cystic masses attached to the left atrial wall. Then TEE was performed which confirmed the presence of two large cystic lesions inside the dilated left atrium and moderate tricuspid incompetence.

CMR was requested and confirmed the presence of a large non mobile cystic extracardiac mass (8.0 x 4.5 cm) with thin smooth borders seen wrapping around and compressing the left atrium and significantly reducing LA volume. The mass appeared trabeculated with multiple internal septae. It encroaches (by left atrial compression) on the mitral valve causing significant functional mitral stenosis. No invasion of adjacent structure is detected. Complete obstruction of upper right and left pulmonary veins is noticed. The left atrium was markedly dilated. The mass elicited a hyperintense signal on T2W images; low to intermediate signal on T1W images and showed no signal drop on Fat-Sat images. There was no uptake of contrast on first-pass perfusion sequence. Also, it showed no inside enhancement on LGE images; however, it is surrounded by significant areas of enhancement. These features correspond to the diagnosis of large inflamed or infected "pericardial or bronchogenic cyst."

Management:

Surgical consultation was done and surgical resection was advocated as the treatment of choice. Histopathologic examination of the lesion showed a lining of respiratory epithelium associated with a wall containing smooth muscle, which is characteristic of bronchogenic cyst in addition to inflammatory cells. After the cyst excision the patient was completely asymptomatic.

Follow Up:
The patient was followed up after surgery and 1 month later clinically and by echo, she was completely asymptomatic with the relief of chest pain and shortness of breath.
























Learning Points from this Case: To emphasize the importance of multimodality imaging in patients presenting with un-explained heart failure.

To consider extracardiac compressive pathologies in the differential diagnosis of heart failure.

CMR is the gold standard for assessing intracardiac and extracardiac masses.

CMR can well characterize cardiac masses and guide surgical planning.

TEE revealed the presence of large oval cystic mass. The mass appears trabeculated with multiple internal septae
SSFP, 4 chamber view and 2 chamber view revealing large oval extracardiac mass seen wrapping around and compressing the left atrium significantly reducing LA volume.
Surgical excision of bronchogenic cyst