Abdominal lymphangioma is an uncommon benign cystic mass. When present, it is more likely to be encountered in children. Only 6% of benign tumors in children are lymphangiomas, and 5% of these are located in the abdomen. The children may present because of abdominal pain related to intestinal obstruction, or they may be asymptomatic with clinical evidence of a compressible mass or ascites. Fever, nausea, vomiting, constipation, or diarrhea may be associated. Because of the compressibility of the mass and the "doughy" consistency on palpation, the full extent of the mass may not be appreciated until cross-sectional imaging is done. Plain radiographs may demonstrate the mass and displacement of the surrounding structures.

Sonographically, lymphangioma generally appears as a complex, mainly septated, cystic compressible mass which is often quite extensive. It generally causes displacement of the ipsilateral kidney and the bowel. With superimposed hemorrhage or infection within the cysts, the anechoic areas may become hyperechoic and the diagnosis may be difficult. The sonographic appearance of lymphangioma is identical to that of mesenteric cyst, and thus these two entities, aside from their different consistencies (mesenteric cysts are generally tense), can be confused. Histologic diagnosis is necessary for definitive differentiation.

CT is essential for preoperative planning, to assess the extent of the mass and the possibility of encasement of bowel loops. These findings may not be appreciated sonographically. The differential diagnosis includes:

1. gastrointestinal duplication cyst. These generally have only one compartment, although multiple separate duplication cysts within the same patient may occur. The wall generally has a hyperechoic inner rim and a hypoechoic outer muscular rim;

2. lymphoma, if it is extremely hypoechoic;

3. ovarian cyst;

4. choledochal cyst. This should be easily differentiated by a history of right upper quadrant pain, jaundice and/or fever and the demonstration of communication of the cyst with biliary ductal system;

5. pancreatic pseudocyst; and

6. inflammatory pseudotumor of the mesentery.

Rarely, lymphangioma may be confused with:

7. severely necrotic exophytic Wilms' tumor, or

8. a multiseptated cystic neuroblastoma.