Mesenteric & Omental Cyst

• • Rare developmental lesions thought to result from the sequestration of lymphatic tissue during development

  • Characterized by thin walls lined with endothelial cells without surrounding smooth muscle

  • Lesions located in the mesentery, omentum, or retroperitoneum

  • Cysts may be filled with serous lymphatic fluid (common in the mesocolon and omentum), or chyle (common in the small bowel mesentery)

  • Most lesions are benign

  • Cysts often become extraordinarily large before producing symptoms

  • Bleeding, rupture, torsion, and infection of the cyst may occur

Epidemiology

• • Mesenteric cysts twice as common as omental cysts

  • 33% of lesions are detected in children, the remainder in adults

  • Symptomatic cysts are usually diagnosed in children before age 10

  • Commonly discovered incidentally on imaging study obtained for other reasons

Symptoms and Signs

• • Soft, mobile abdominal mass

  • Chronic abdominal pain

  • Acute abdomen

  • Obstructive symptoms

  • -Nausea

    -Vomiting

    -Abdominal distention

Imaging Findings

• • Abdominal x-ray: May demonstrate displacement of the viscera by the cyst

  • Contrast study may help differentiate between an intestinal duplication and a mesenteric or omental cyst

  • US: Demonstrates a thin-walled hypoechoic homogenous mass that may be uniloculated or multiloculated

  • CT scan: Demonstrates a thin-walled fluid density mass that may be uniloculated or multiloculated

• • Pancreatic pseudocysts

  • Enteric duplication

  • Echinococcal cysts

  • Inflammatory cysts

  • Retroperitoneal tumors

  • Tumor metastasis

  • Abscess (especially from perforated appendicitis)

  • Large ovarian cysts

  • Localized fluid collection

  • Hematoma

  • Biloma

  • Urinoma

  • Ascites

  • Mesenteric lipodystrophy

  • Primary peritoneal mesothelioma

  • Pseudomyxoma peritonei

Rule Out

• • Abscess

  • Primary or metastatic neoplasm

• • Thorough history assessing for abdominal trauma, symptoms and risk factors for pancreatitis (alcoholism, cholelithiasis) or constitutional symptoms (such as weight loss and fatigue)

  • CBC

  • Basic chemistries

  • Amylase and lipase

  • UA

  • Abdominal pelvic CT scan with IV and PO contrast

When to Admit

• • Acute complications only

  • Asymptomatic cyst can be managed as outpatient

When to Refer

• • Children best managed operatively by a pediatric surgeon

• • Simple excision of the cyst without resection of adjacent organs or major neurovascular structures

  • Partial excision with marsupialization alternative when complete excision not possible

  • Internal intestinal drainage also an option, particularly if cyst is adjacent to the intestinal wall and there is concern that the cyst may actually be an enteric duplication

Surgery

Indications

• • Definitive diagnosis and treatment

Contraindications

• • Patients medically unfit for operation

Treatment Monitoring

• • Abdominal exam for mass redevelopment

  • Consider US screening for patients ...