Which is the second most common benign liver tumor and how does it present on ultrasound?

• A. Cavernous hemangioma: Homogeneous, hyperechoic, round, smaller than 3 cm
• B. Focal nodular hyperplasia (FNH): Isoechoic, solid, smaller than 5 cm
• C. Hepatic adenoma: Heterogeneous, hypoechoic
• D. Simple hepatic cyst: Anechoic, posterior enhancement

Answer: (B)

FNH is the second most common benign liver tumor, and its ultrasound appearance reflects its solid, vascular nature while often blending with normal liver tissue. On gray-scale ultrasound it typically appears as a solid lesion that is isoechoic to the surrounding liver parenchyma, usually well circumscribed and smaller than about 5 cm. The central scar is a classic MRI/CT feature but is not reliably seen on ultrasound; Doppler can show arterial flow within the lesion, consistent with its hypervascularity. This combination—solid, iso-echoic, and generally under 5 cm—best fits focal nodular hyperplasia.

For context, cavernous hemangiomas are often very bright (hyperechoic) on ultrasound, hepatic adenomas can be heterogeneous or variable in echogenicity due to fat or hemorrhage, and simple cysts are anechoic with posterior acoustic enhancement.