Prenatal diagnosis of a retroperitoneal lymphangioma: a case and review.

Prenatal sonographic findings of lymphangiomas characteristically appear as thin-walled, multiseptate hypoechogenic masses. In our case, a retroperitoneal hypoechogenic mass was detected at 26 weeks of gestation by sonography. Serial sonographic examinations demonstrated multiple septations at 29 weeks of gestation, which in retrospect was a classical finding of retroperitoneal lymphangioma. MRI at 38 weeks of gestation revealed a multilocular mass, which was homogeneous, low on T1-weighted and high on T2-weighted images, in the left retroperitoneal cavity. These findings were compatible with the diagnosis of a lymphangioma. This case shows the change in characteristic imaging features, from a unilocular to multilocular pattern, of a lymphangioma with regard to gestational age. It is important to observe the size and extension of such tumors in order to determine the prospect for neonatal prognosis, as well as to make decisions on the delivery timing and style.