This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Solitary hypoechoic lesion of the liver without septa or debris is most likely to be - \nSelect and explain. \nA. Hydatid cyst, B. Carolis disease, C. Liver abscess, D. Simple cyst', 'role': 'user'}, {'content': "Answer: D \nExplanation: 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.\nSimple 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.\n\nUltrasound appearances of -\nHydatid cyst -\nIt presents either as a simple cyst with hydatid sand or daughter cysts or floating endocyst or calcification.\nCaroli's disease -\nIts the type V choledochal cyst\nMultiple intrahepatic biliary cysts are seen on ultrasound. Sludge & stones may also be visible within the cysts.\nLiver abscess -\nSonographic appearance may include a cystic lesion with floating internal echoes and irregular margins.\nSeptations, debris and fluid-fluid interfaces may also be seen.", 'role': 'assistant'}]