Omental lymphangioma is a rare benign vascular malformation developing within the greater or lesser omentum — a cystic lesion composed of dilated lymphatic channels. Usually diagnosed in children and young adults but can be detected at any age. It has a multilocular cystic structure with thin septa separating compartments containing water or chylous density fluid. On CT, a thin-walled, multilocular cystic mass with homogeneous water or fat density fluid compartments is seen. On MRI, it shows markedly hyperintense T2 signal, hypointense (water) or hyperintense (chylous/hemorrhagic) T1 signal. Lymphangiomas do not undergo malignant transformation but complications (hemorrhage, infection, rupture, torsion) can cause acute presentation. Surgical excision is preferred in symptomatic cases.
Age Range
1-50
Peak Age
25
Gender
Equal
Prevalence
Rare
Omental lymphangiomas are congenital lymphatic system malformations — resulting from failure of complete connection between the lymphatic sac (jugular sac) and venous system during embryological development. Sequestered lymphatic tissue continues to produce lymphatic fluid but cannot drain — resulting in cystic cavities composed of dilated lymphatic channels. These cystic spaces lined by endothelial cells contain serous, chylous, or hemorrhagic fluid. Chylous fluid (fat density, -10 to 20 HU) reflects the connection of lymphatic channels with small bowel lymphatics — chylomicrons pass into the lymphatic system during fat absorption and accumulate in lymphangioma cavities. Therefore CT fluid density varies between water (0-20 HU) and fat (-10 to 20 HU), and chylous compartments show high T1 signal on MRI. Septae consist of fibrovascular stroma and smooth muscle cells — thin septae may enhance but thickened septae or solid nodules suggest complication (hemorrhage, infection) rather than malignant transformation. The omental location of lymphangiomas shows intraperitoneal spread pattern — as the tumor grows it expands the omentum in a leaf-like fashion and displaces bowel loops.
Thin-walled multilocular cystic mass in omentum with different fluid densities (water to fat density) in different compartments — this density heterogeneity reflecting chylous content is the most diagnostic CT finding for lymphangioma.
Thin-walled, multilocular cystic mass in omentum. Compartments separated by thin septa (<2 mm), each containing homogeneous fluid density (0-20 HU). Mass borders are smooth and well-defined, displacing surrounding bowel loops. Septa may show minimal enhancement on contrast CT. No solid component, papillary projection, or mural nodule — if present, complication or alternative diagnosis should be considered.
Report Sentence
Thin-walled, multilocular cystic mass in the omentum, consistent with lymphangioma.
On non-contrast CT, some cystic compartments show fluid at fat density (-10 to 20 HU) — reflecting chylous (lymph + chylomicron) content. Different compartments may show different densities: some at water density (0-20 HU), others at fat density (-10 to 10 HU). This density variability is a distinguishing finding for lymphangioma.
Report Sentence
Fluid varying between water and fat density in cystic compartments, consistent with chylous content supporting lymphangioma.
On T2-weighted sequence, all cystic compartments show markedly hyperintense signal — like free fluid. Septa appear as thin low-signal lines on T2. Hemorrhagic compartments may show slightly lower T2 signal (hemosiderin effect). On fat-suppressed T2, chylous compartments retain signal (chylous fluid is not macroscopic fat — chylomicrons in emulsion form), while pure fat (lipoma) is suppressed.
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Markedly hyperintense signal in all compartments with thin hypointense septa on T2, consistent with cystic lymphangioma.
Variable T1 signal between compartments: serous fluid compartments hypointense (long T1), chylous compartments intermediate-to-high signal (fat content shortens T1), hemorrhagic compartments hyperintense (methemoglobin T1 shortening). This signal heterogeneity reflects different contents of lymphangioma cavities and distinguishes from other cystic lesions.
Report Sentence
Variable T1 signal between compartments (hypointense to hyperintense), reflecting serous, chylous, and hemorrhagic contents consistent with lymphangioma.
US shows multilocular cystic mass with anechoic or hypoechoic fluid, separated by thin septa. Posterior acoustic enhancement is present (evidence of cystic nature). Septa are thin, smooth, and avascular (no flow on Doppler). Low-level internal echoes may be seen in chylous compartments. In complicated lymphangioma (hemorrhage), echogenicity increases and fluid-debris levels may be seen.
Report Sentence
Multilocular cystic mass with thin septa and anechoic fluid at the level of the omentum on US, consistent with lymphangioma.
Lymphangioma grows in an insinuating pattern between adjacent structures — extends between bowel loops, displaces organs but does not invade. Bowel loops may appear surrounded by the mass but bowel wall is intact. This growth pattern is characteristic of benign lesion and distinguishes from aggressive solid tumors.
Report Sentence
The cystic mass grows in an insinuating pattern between bowel loops without invasion findings — consistent with benign lesion pattern.
Criteria
Composed of small, thin-walled lymphatic channels. Usually small (<5 cm). More common in skin and subcutaneous tissue, omental location rare.
Distinct Features
CT/MRI: microcystic pattern — multiple small cysts (<1 cm) together. 'Stained glass' appearance on US.
Criteria
Composed of dilated lymphatic channels. Medium-sized, may contain cystic and solid components. Intra-abdominal location more common in this subtype.
Distinct Features
CT: mixed cystic-solid appearance, septa may be thicker. MRI: heterogeneous T2 — solid stroma low signal, cystic areas high signal.
Criteria
Most common subtype — composed of large, multilocular cystic cavities. This is the typical form in omental location. Compartments >2 cm diameter.
Distinct Features
CT: classic multilocular cystic mass, thin septa, water/fat density fluid. MRI: very hyperintense T2, variable T1. US: anechoic compartments.
Distinguishing Feature
Mucinous cystadenoma is ovarian origin with more homogeneously hyperintense mucinous fluid on T1. Omental lymphangioma has no ovarian connection, inter-compartmental density/signal variability (chylous vs serous) is typical.
Distinguishing Feature
Pseudomyxoma peritonei: diffuse peritoneal mucinous implants, omental caking, scalloping. Lymphangioma: focal cystic mass, no peritoneal implants or omental caking.
Distinguishing Feature
Mesenteric cyst usually unilocular, thin-walled, homogeneous water density. Lymphangioma is multilocular with septa and inter-compartmental density variability (chylous) is typical.
Distinguishing Feature
Cystic mesothelioma: multiple thin-walled cysts adherent to peritoneal surfaces, ascites common, asbestos history. Lymphangioma: focal omental mass without peritoneal adherence pattern.
Urgency
routineManagement
surgicalBiopsy
Not NeededFollow-up
12-monthConservative follow-up (annual US) is sufficient for asymptomatic small lymphangiomas. Surgical excision is preferred for symptomatic cases (pain, compression, complication). Laparoscopic approach is possible. Complete excision reduces recurrence risk — 10-15% recurrence with incomplete resection. Sclerotherapy (ethanol, bleomycin, OK-432) is an alternative but has higher recurrence rates than surgical resection in omental location. No malignant transformation risk. Complications (hemorrhage, infection, torsion) may require emergent surgery.
Lymphangiomas are benign lesions but may require surgery due to their size. Complete surgical resection is curative but may be difficult due to insinuating growth around structures. Recurrence may occur after incomplete resection. There is no risk of malignant transformation.