Presentation
Staging evaluation for lymphoma.
Patient Data
A cystic lesion located between hepatic segment 6, right iliac muscle, and right upper kidney measures 4.5 x 2.3 x 4.1 cm. It abuts the liver capsule and there is a possible intervening fat-plane.
ROI measurements of internal density on pre- and post-contrast sequences are compatible with fluid attenuation and likely pseudo-enhancement.
Periportal lymphadenopathy is related to patient's known lymphoma. There is a cyst in the liver adjacent to gallbladder fossa. Two low-density lesions in pancreatic body/tail may represent side-branch intraductal papillary mucinous neoplasia.
FDG PET-CT shows the absence of avidity associated with the right perihepatic lesion.
Separately, the periportal/pancreatic lymphadenopathy is hypermetabolic in keeping with lymphoma.
No change in the retrohepatic cystic lesion at 14 months.
Case Discussion
Posterior parahepatic cysts are indolent cystic lesions which need to be differentiated from diaphragmatic pseudotumour (due to diaphragmatic slip) and retroperitoneal metastasis. They have been hypothesised to represent lymphangiomas, mesothelial cysts, duplication cysts or other embryological remnant 1.
In this case, the lesion is clearly separate from the diaphragm on coronal views, non-enhancing, stable over >1 year, and entirely non-avid on FDG-PET, essentially confirming its benignity.