ABSTRACT
The authors present a rare case of giant mediastinal cyst which arises from the thymus gland, and goes down in both pleural spaces, especially in the right chest cavity where a dominant part of the cyst was present. The cyst was full with 2.5 liters of transparent fluid, and compressed surrounding structures - heart and both lungs, especially the right one which was partially collapsed. The patient was a 52 years old woman, without any clinical symptoms. Accidentally, on the screened chest X-ray a shading in the distal third of the right chest was detected. The case was well documented with a CT of the chest, and an indication for surgical treatment was made. The surgery was done successfully in general anesthesia according to the small right anterior thoracotomy from which a giant part of the cyst was mobilized, which was in the right pleural cavity, but, also, the thymus with the origin of the cyst in the anterior and superior mediastinum was completely removed. In the end, a part of the cyst which was in the left pleural cavity was removed.
