Chapter 1 of 6 · Fundamentals
Definition & pathophysiology
Definition, Epidemiology, and Pathophysiology of Mesenteric and Omental Cysts
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What the experts said
About 60% of mesenteric and omental cysts are diagnosed by age 15
The leading theory is that mesenteric and omental cysts arise from benign proliferation of lymphatics within the mesentery that do not communicate with the lymphatic drainage system
Mesenteric and omental cysts are true cysts with an epithelial lining, as opposed to pseudocysts which do not have epithelial lining
Mesenteric cysts are more common than omental cysts
About 60% of mesenteric cysts are in the small bowel mesentery, 25% in the large bowel mesentery, and the remainder in the retroperitoneum
Small bowel mesentery cysts are more often chylous in nature, whereas large bowel and retroperitoneal cysts are more likely to be serous
Mesenteric cysts are more common in the ileal mesentery
In adults, mesenteric and omental cysts can often be asymptomatic or incidentally found, but 40-60% of children present with symptoms
Symptoms of mesenteric and omental cysts include abdominal distension, vomiting, weight loss, fever, and acute abdominal pain
Acute abdominal pain from mesenteric cysts can be related to hemorrhage into the cyst or intestinal ischemia from torsion of the cyst within the bowel and mesentery
Mesenteric and omental cysts can present as acute or intermittent bowel obstruction
Ultrasound is the first choice for imaging in patients with suspected mesenteric or omental cysts
On ultrasound, mesenteric cysts appear as hypoechoic cystic masses with internal septations or small hyperechoic foci related to hemorrhage
Imaging should determine whether the cyst is macrocystic or microcystic because this changes the treatment approach
Cross-sectional imaging with CT (with PO and IV contrast) or MRI is often obtained after ultrasound to delineate the mass from bowel and evaluate fat planes and soft tissue
The differential diagnosis for abdominal cystic masses in children includes enteric duplication cysts, ovarian cysts, paratubal cysts, choledochal cysts, pancreatic/splenic/renal cysts, echinococcal cysts, urachal cysts, and hydronephrosis
Microcystic or mixed micro/macrocystic mesenteric cysts are often treated initially with sirolimus
Mixed lesions can be treated with sirolimus in combination with sclerotherapy
Macrocystic mesenteric cysts are often treated initially with aspiration and sclerosis to reduce the cyst and symptoms without requiring surgical resection
Sclerotherapy agents include 10% glucose, ethyl alcohol, or doxycycline mixed with saline
After sclerotherapy, at least 3 months should elapse before considering surgery to allow the inflammatory reaction to subside
The goal of surgical resection should be complete excision of the cystic lesion
Surgical resection can be performed open or laparoscopically depending on surgeon comfort and cyst location
Because cysts can be integrated into the mesentery and intestinal blood supply, small bowel or large bowel resection may be required
If complete cyst removal would require extensive bowel resection, marsupialization with sclerosis can be used to manage the cyst and reduce recurrence
Pedunculated mesenteric cysts are easier to resect and may not require bowel resection
Sessile cysts that are incorporated within the mesentery often require bowel resection at the time of cyst resection
Mesenteric cysts can extend into the retroperitoneum and involve the IVC or aorta, making them difficult or impossible to excise
Mesenteric cysts can be multicentric or complex with different lobules, and treatment and prognosis depend on the nature and location of the cyst
The major risk after aspiration and sclerosis is recurrence, which may require secondary surgical intervention
Recurrence risk is between 0-15% depending on the approach, and is higher with marsupialization
There are no standardized guidelines for follow-up frequency or whether imaging is required versus history and physical alone
The prognosis for children with mesenteric and omental cysts is quite good
Patients should be followed at routine intervals to ensure the cyst does not recur and cause additional symptoms