[Abdominal echography in the diagnosis and monitoring of retroperitoneal fibrosis. Apropos of 2 cases].

The authors report 2 new cases of unilateral ureteral obstruction due to a retroperitoneal fibrosis diagnosed by ultrasound examination. Retroperitoneal fibrosis presents as a hypo-echogenic, homogeneous mass, anterior to the sacral promontary, extending more or less cranially or caudally around the aorta and the iliac vessels where it gets a circumferential appearance. The complete regression of the mass has been followed by ultrasound on one patient. The authors underline the diagnostic problem posed with the R.P.F. secondary to metastatic neoplasm and discuss the place of ultrasound guided fine needle biopsy performed on one patient for the diagnosis of the affection.