The retrocrural lipoma is a rare but important site for occurrence of lipoma as it is liable to malignant transformation, normally the retrocrural space contains a crescent rim of fat that support the retrocrural content; azygos, hemiazygos and cisterna chyli.

Here an un expected herniation of the left perinephric fat in the left side of the retrocrural space is suggected rather than lipoma due to the presence of left crural defect with concomitant multiple string like vessels running between the two spaces.