What is a rare fatty tumor of the liver that appears as a hyperechoic mass?

A hepatic lipoma is a rare fatty tumor of the liver that is characterized by its appearance as a hyperechoic mass on ultrasound. This echogenicity is due to the high fat content, which reflects sound waves more than the surrounding liver tissue, making it easily identifiable on an ultrasound. Hepatic lipomas are uncommon, especially compared to other liver lesions, which is why identifying the correct answer in this context is crucial.

In contrast, hepatic adenomas are benign tumors of the liver that also appear as hypervascularized masses but are typically less echogenic than lipomas. Cavernous hemangiomas, the most common benign vascular tumors of the liver, are usually hyperechoic as well but different in nature since they are vascular lesions rather than true fatty tumors. Metastatic tumors can present with variable echogenicity depending on their composition, but they are not classified as fatty tumors.

Thus, hepatic lipoma stands out as the correct answer because of its unique characteristics as a rare fatty tumor that specifically appears as a hyperechoic mass in the liver.