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Pyogenic liver abscess - cluster sign

Case contributed by Bijaya Shrestha
Diagnosis almost certain


Right upper quadrant pain for one week. Intermittent fever. Vomiting, multiple episodes

Patient Data

Age: 65 years
Gender: Male

There is a large, well-defined hypodense lesion with septations and cluster sign involving the segments VI and VII in the right lobe of the liver. It measures approximately 9.6 cm x 10 cm x 11 cm. These lesions show peripheral enhancement on the arterial phase that persists in the portal and delayed phase with non-enhancing central areas of diminished attenuation on post-contrast studies. A few enhancing septa are also present in the lesion.

Mild right reactionary pleural effusion.

Case Discussion

The cluster sign is a finding associated with pyogenic liver abscesses. It is better appreciated on contrast-enhanced CT and MRI images. The sign describes the coalescence of multiple tiny abscesses into a single larger abscess cavity with peripheral rim enhancement on post-contrast studies, giving a clustered appearance. 

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