Typically water density (near 0 HU) or chylous (< -20 HU), and only rarely hemorrhagic
No internal enhancement
Can be multiloculated (± septations) with “feathery” appearance
Soft lesions without mass effect: Easily indented by surrounding structures, such as mesenteric vessels/bowel
Usually hypointense on T1WI MR and hyperintense on T2WI
TOP DIFFERENTIAL DIAGNOSES
• Loculated ascites
• Gastrointestinal duplication cyst
• Pancreatic pseudocyst
• Peritoneal inclusion cyst
• Cyst or cystic tumor arising from visceral organ
CLINICAL ISSUES
• Symptoms are rare (particularly in adults)
Rare symptoms due to mass effect, superinfection, or internal hemorrhage
• Surgery is treatment of choice when necessary
DIAGNOSTIC CHECKLIST
• Differentiate from other primary cystic lesions or tumors of visceral organs
(Left) Axial CECT shows a complex cystic mass in the mesentery sandwiching a small bowel segment . The mass is near water density and has small foci of calcification in its septa and peripheral walls . The soft nature of the mass is indicated by the absence of bowel obstruction.
(Right) Axial CECT shows a complex water-density mass in the mesentery, immediately adjacent to the pancreas and duodenum. The mass is divided by multiple septa , which, like the peripheral walls, are thin.
(Left) Axial CECT in a female patient shows a large, cystic mass with multiple septations filling much of the lower abdomen. Note the calcifications in the septa and the peripheral walls.
(Right) Axial CECT in a female patient shows a cystic retroperitoneal mass with subtle septa and a small focus of calcification . The mass was resected and found to contain chylous fluid (typical of a lymphangioma) and an epithelial lining, features that help account for the variety of names for this tumor.
. The mass is near water density and has small foci of calcification in its septa and peripheral walls 
. The soft nature of the mass is indicated by the absence of bowel obstruction.
, which, like the peripheral walls, are thin.
filling much of the lower abdomen. Note the calcifications 
in the septa and the peripheral walls.
with subtle septa and a small focus of calcification 
. The mass was resected and found to contain chylous fluid (typical of a lymphangioma) and an epithelial lining, features that help account for the variety of names for this tumor.
Typically water density (near 0 HU) or chylous (< -20 HU), with lesions rarely demonstrating hemorrhagic contents
