Lymphangioma of the retroperitoneum: CT and sonographic characteristic.

The authors retrospectively evaluated radiologic, clinical, and pathologic findings in 19 cases of lymphangioma of the retroperitoneum. The tumors were judged confined to one compartment of the retroperitoneum in 68% of the cases, whereas in 32% of cases the tumor involved more than one compartment. Abdominal radiography depicted the mass in all cases. Excretory urography demonstrated organ displacement without tumor invasion in all cases. Sonography showed multiloculated fluid in 61% of cases and a unicameral mass in 39% of cases. All but one of the multiloculated lymphangiomas had thick septa. Sonography also depicted the fluid as uncomplicated in 56% of cases. The remainder had debris that sometimes layered in the dependent portion of the cyst. Computed tomography (CT) showed a unicameral mass in 57% and a septated mass in 43% of cases. CT also showed thin, smooth walls in 79% and thick, irregular walls in 21% of cases. At CT the fluid contents were found to be homogeneous and of fluid attenuation in 64% and were complex in 36% of cases. The attenuation of fluid in one case was the same as that of retroperitoneal fat. In two cases the mass contained mural calcification. The most characteristic radiologic finding of lymphangioma of the retroperitoneum is an elongated tumor containing uncomplicated fluid with or without septa. Chyle and mural calcification are very uncommon in this location.