A large midline mass with dimensions of 10.1 x 8.2 x 11 .7 cm (transverse x AP x longitudinal) destroys the distal sacrum from the level of the inferior aspect of S3, and extends cranially to fill the sacral canal to the level of S2/3. The mass is well circumscribed and internally heterogeneous, but predominantly of fluid density with internal septations and coarse calcification. The rectum is flattened and displaced anteriorly but the intervening fat plane is preserved.