Case 377: Fascioliasis

Diagnostic Category:

Clinical Presentation:

52 year-old man from Switzerland with incidental finding in his liver on CT done for evaluation for deep vein thrombosis after presenting with pain and swelling of his right lower extremity. Patient enjoys walking in nature with his wife picking blueberries and rasberries, which he enjoys eating right away after washing them in nearby creeks. He also enjoys time with his grandchildren, playing and whistling through pipes, which he forms by rolling large grass leaves.

US: Necrotic demarcation of infested parenchyma on CEUS

Imaging Findings:

Gray-scale ultrasound of segment 8 demonstrates a cluster of hypoechoic nodules without capsule, halo or increased acoustic penetration or shadowing.

Color and power Doppler demonstrate surrounding and transgressing vessels ("penetrating-vessel-sign").

Contrast enhanced ultrasound demonstrates nodular confluent areas of little or no enhancement, which partly show configuration of pearls on a string, representing necrotic parenchyma and debris as a result of parasitic infestation with fasciola hepatica. Demarcation of necrotic parenchymal portions is better seen on later contrast phases.

The parasite (20-30mm in length and 13mm thick) penetrates the hepatic capsule through the gastrointestinal tract and feeds on hepatic parenchyma. Pearls-on-string appearance is a result of one or a few parasites moving from one location to another leaving behind necrotic liver portions. If pearls-on-string appearance is not identified or recognized, nodular formations may mimic abscess in early stages or malignancy.

Note hyperemic parenchyma in between and surrounding the necrotic portions does not allow clear distinction from peripheral lesional enhancement often seen in malignancies. Hyperemia due to inflammation and hypovascular or avascular irregularly defined foci are typical for granulomatous or parasitic infections (see also alveolar echinococcosis).

Courtesy Dr. Gerd Stuckmann, Institute for Radiology and Nuclear Medicine, Kantonsspital Winterthur,  Switzerland.