Mediastinal cavernous lymphangioma is a rare mediastinal lesion and its association with lupus erythematosus has not yet been reported in the literature. We present a 25 year-old female with lupus erythematosus who had bilateral massive refractory and recurrent pleural effusion as well as ascites for a long period of time. During surgery, a huge multicystic lesion with a thick wall, covering the entire parietal and visceral pleura was found, which was subsequently proven to be a cystic cavernous lymphangioma.