Bronchogenic cyst presenting as mediastinal mass with pleural effusion.

Mediastinal bronchogenic cysts are usually identified on computed tomography (CT) as well-defined masses of variable density that may contain rim calcifications. Pleural effusion has never been described in association with these cysts. We report two cases of bronchogenic cysts with unusual presentation because of an association with a pleural effusion not explained by pulmonary infection. The patients were studied with CT scan (n = 2) and magnetic resonance imaging (MRI) of the chest (n = 1). In the first case, the pleural effusion directed diagnosis towards lung tumour; and the diagnosis of bronchogenic cyst was made on thoracotomy. In the second case, bronchogenic cyst was suspected on MRI findings. Inflammatory reaction was also suspected on the CT scan, which showed enhancement of the cyst edge. In both cases, surgical excision of the cyst was difficult because of pericystic adhesions to adjacent organs. Therefore, solely on the finding of a pleural effusion, pericystic inflammation had to be suspected.