Retroperitoneal, mesenteric, and omental cysts.

Retroperitoneal, mesenteric, and omental cysts are rare abdominal tumors occurring in approximately one of 105,000 hospitalized patients. These cysts have a similar pathogenesis that primarily may be ectopic lymphatic tissue. Retroperitoneal and mesenteric cysts can occur anywhere in the area between the duodenum and rectum but are most common in the small-bowel mesentery, especially the ileum. They can appear as chronic abdominal pain, a painless abdominal mass, or acute abdomen. The most common physical finding of a retroperitoneal or mesenteric cyst is a compressible abdominal mass, movable transversely but not longitudinally; omental cysts are freely movable. Diagnostic aids include abdominal computed tomography and ultrasound. The upper gastro-intestinal (GI) tract series, barium enema examination, and intravenous pyelogram exclude GI and genitourinary cysts and tumors. Treatment of choice is enucleation; resection of the adjacent bowel may occasionally be necessary. Morbidity and mortality should be very low because of modern surgical techniques and follow-up procedures.