Bronchogenic Cyst-MRI

Middle aged lady with non specific respiratory symptoms for evaluation on Xray showing opacity. CT suggested cyst. MR shows a well defined, regular, approximately 6 cm sized predominantly fluid signal intensity, thin walled space occupying lesion seen in the left anterior mediastinum with mass effect on the ipsilateral lung parenchyma, and great vessels particularly the arch of the aorta and pulmonary trunk. There is no fluid / fluid level. Features are suggestive of Bronchogenic cyst.

 Case by Dr MGK Murthy

Teaching points :

- Congenital in nature derived predominantly from foregut diverticulum.

- Constitutes 40-50% of all mediastinal cyst.

- Seen as asymptomatic or nonspecific mass effect symptoms in the form of vascular or lung compression, with increase incidence in males predominantly.

- Usually fluid signal on all studies with possible T1 hyperintensity suggesting proteinaceous contents with no water lilly sign or nodules or septae or fluid blood levels or calcification.

- Differential diagnosis includes parasitic ( water lily sign would help for hydatid), teratoma ( fat or calcification ), thymic, ( nonhomogenous, presence of thymomegaly ), ectopic thyroid, ( intense uptake of iodine based contrast agents with heterogenity), great vessels aneurysms, ( presence of flow signal abnormality, calcification ), and nonspecific etiology.

- CEMR would usually help exclude enhancing nodule within, which could suggest malignant transformation, as squamous metaplasia is a known sequale.