Posterior parahepatic cyst

Case contributed by Dr Brian Gilcrease-Garcia

Presentation

Staging evaluation for lymphoma.

Patient Data

Age: 60 years
Gender: Female
CT

Initial CT

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.

Nuclear medicine

FDG PET-CT

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.

CT

14 month follow up CT

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 pseudotumor (due to diaphragmatic slip) and retroperitoneal metastasis. They have been hypothesized 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.

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Case information

rID: 68449
Published: 31st May 2019
Last edited: 1st Jun 2019
Inclusion in quiz mode: Included
Institution: Mallinckrodt Institute of Radiology at Washington University

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