Wheel within a wheel sign (hepatic candidiasis)

The wheel within a wheel sign describes one of several possible ultrasound findings of hepatic candidiasis. The finding consists of a round lesion with three layers corresponding to the following histopathological changes :

• peripheral hypoechoic area (fibrosis)
• middle hyperechoic area (inflammatory cells)
• central hypoechoic area (necrosis)

The histopathologic correlates were shown via an animal model.

This appearance is in contrast to the more common bull’s-eye sign ultrasound finding, which consists of a central echogenic nidus surrounded by a hypoechoic rim.