Retroperitoneal lipomatosis--report of two cases with an unusual distribution.

Two cases of retroperitoneal lipomatosis with an unusual distribution are reported. In the first case the fat was confined to the perirectal soft tissues and the sigmoid mesentery, whereas in the second case it was peripancreatic and extended into the small bowel mesentery. The lipomatous nature of these retroperitoneal masses was suggested by the lucency of the fat on the plain abdominal roentgenograms. These cases were studied prior to the availability of computed tomography, so that the diagnoses were confirmed by surgical exploration, which may have been avoided by this currently available noninvasive technique.