[Three cases of retroperitoneal cystic lymphangioma]

Retroperitoneal cystic lymphangioma is a rare benign tumor. Three cases of retroperitoneal cystic lymphangioma with histological proof were reported. Every case revealed similar characteristic appearances on CT, such as 1. unilocular or multilocular cystic mass with homogeneous near-water density, 2. non-enhanced or slightly enhanced wall and septum, 3. commonly thin wall without irregularity, 4. compression of surrounding organs with sharp margin. No secondary changes such as hydronephrosis and ischemic change were noted in the surrounding compressed organs, revealing that this tumor is soft and the growth is slow. Several differential diagnoses were considered, but diagnosis was not so difficult on CT, considering anatomical relations and clinical appearances.