Intra-abdominal Cysts & Lymphangiomas
Intra-abdominal cysts and lymphangiomas are relatively common prenatal diagnoses. Mesenteric cysts are estimated to occur in one in 20,000 pediatric admissions, while omental and retroperitoneal cysts are less common. Most lymphangiomas are found outside the abdomen, but of intra-abdominal sites, the most common site is retroperitoneum, followed by the mesentery, according to specialists at the University Center for Fetal Medicine.
Ultrasound imaging of these lesions shows very thin walls and no peristalsis. Doppler ultrasound showing no blood flow in the wall and the absence of peristalsis makes a simple cyst or lymphangioma more likely.
Fetal MRI can be also helpful to distinguish retroperitoneal lymphangiomas from the surrounding vascular and soft tissues. Pictured (right) is a MRI of a fetus with large cystic structure in the left retroperitoneum, indicated by the arrow. The cyst is filled with fluid, has several internal septations and surrounds the left kidney, all consistent with a retroperitoneal lymphangioma.
Although both abdominal cysts and lymphangiomas are frequently asymptomatic, acute episodes of abdominal pain, obstructive symptoms or anemia from hemorrhage into the lesion have been seen. Postnatal ultrasound should be done to confirm the diagnosis, and a CT scan or MRI may help define its relationship to the surrounding organs.
Surgical resection is recommended because of the acute complications. However, this may not be possible if there is extensive involvement of the surrounding structures. In this case, drainage and sclerotherapy remain an option, but this treatment may require multiple procedures.
Early complications may require a period of "bowel rest" for resolution. In large mesenteric cysts and lymphangiomas, there is a significant risk of short-gut syndrome after complete resection, and this must be considered against the possible complications of incomplete resection and recurrence.