Solitary hypoechoic lesion of the liver without septa or debris is most likely to be

A solitary hypoechoic lesion without any septae or debris is most likely to be a simple cyst. However rarely a hydatid cyst can have a similar sonologic appearance. Simple cysts are the most common benign lesions found in liver. On imaging studies they appear as unilocular, homogenous fluid-filled structures with a thin wall without projections, septa or debris. Ultrasound appearances of - Hydatid cyst - It presents either as a simple cyst with hydatid sand or daughter cysts or floating endocyst or calcification. Caroli's disease - Its the type V choledochal cyst Multiple intrahepatic biliary cysts are seen on ultrasound. Sludge & stones may also be visible within the cysts. Liver abscess - Sonographic appearance may include a cystic lesion with floating internal echoes and irregular margins. Septations, debris and fluid-fluid interfaces may also be seen. Ref : Rumack's Diagnostic Ultrasound 3rd/e, p. 86, 89, 94, 1865