What is an omental cyst?

What is an Omental Cyst

An omental cyst is a rare benign intra-abdominal cystic lesion that arises from the omentum (the fatty tissue that hangs from the stomach and covers the intestines), most commonly presenting as an asymptomatic abdominal mass or with vague abdominal symptoms. 1, 2

Clinical Characteristics

Epidemiology and Presentation

• Omental cysts are among the least common types of intra-abdominal cystic lesions 3
• They occur predominantly in children, though adults can be affected 2, 4
• Most patients present with abdominal distention and a painless, freely movable abdominal mass 1
• In pediatric cases, acute abdomen due to intestinal obstruction or torsion of the cyst pedicle may occur 2, 3
• Many cases present with vague abdominal pain or are discovered incidentally on imaging 1, 2

Anatomical Location

• Omental cysts typically arise from the greater omentum, though they can originate from the lesser sac 2
• The cysts may have a pedicle arising from structures like the greater curvature of the stomach 3
• They can span large portions of the abdomen, from the stomach to the bladder 2

Diagnostic Approach

Imaging Modalities

• Ultrasonography is the initial diagnostic tool and typically identifies a cystic abdominal mass, though the specific diagnosis of omental cyst is made preoperatively in only 24% of cases 4
• Computed tomography (CT) scan provides definitive characterization of the cystic structure and its relationship to surrounding organs 1, 2
• The most common physical finding is a freely movable abdominal mass that should be included in the differential diagnosis of intra-abdominal masses 1

Differential Diagnosis Considerations

• Omental cysts are often initially misdiagnosed as ovarian cysts in females 1
• Other differential diagnoses include mesenteric cysts, appendicitis (in acute presentations), and other intra-abdominal pathologies 2, 4

Histopathology

• The majority of omental cysts are lymphangiomas histologically 4
• Rare variants include epidermoid cysts within the omentum 5
• The cysts typically have thin walls that can make surgical resection technically challenging 2

Management

Surgical Treatment

• Complete surgical excision is the treatment of choice for omental cysts 1, 2, 3
• Laparoscopic resection is an attractive alternative to open laparotomy when feasible, avoiding large abdominal incisions 3
• However, laparotomy is reasonable when the cyst's anatomical characteristics (thin walls, intimate association with organs like the pancreas, or large size) make minimally invasive approaches unsafe 2
• Complete resection was accomplished in 82% of cases in one series 4

Prognosis and Follow-up

• Recurrence and malignant transformation are rare 1
• Complete resection typically results in a recurrence-free postoperative course 2
• Long-term follow-up is advisable because recurrence can occur, even into adulthood, particularly when complete excision was not achieved 4
• In cases requiring partial excision with marsupialization, recurrence rates are higher (approximately 14% in one series), though reexploration is rarely necessary 4

Common Pitfalls to Avoid

• Misdiagnosis as ovarian pathology is common, particularly in female patients, leading to incorrect preoperative planning 1
• Attempting laparoscopic resection in all cases without considering anatomical complexity can lead to cyst rupture or incomplete resection 2
• Failure to consider omental cyst in the differential diagnosis of pediatric acute abdomen or abdominal masses delays appropriate management 2, 4