Primary multilocular cystic undifferentiated (embryonal) sarcoma of the liver in childhood resembling hydatid cyst of the liver.

Undifferentiated (embryonal) sarcoma (UES) is a very rare primary malignant tumour of the liver; typically presenting in later childhood. This tumour usually appears on CT and ultrasound as a predominantly solid mass with or without cystic areas. We report a case of primary UES which had a multilocular cystic appearance resembling a hydatid cyst on imaging.