Undifferentiated embryonal sarcoma of the liver presenting as a hemorrhagic mass in a pregnant woman.

We present a case of undifferentiated embryonal sarcoma of the liver (UES), an uncommon malignant mesenchymal tumor that occurs predominately in children and is very rarely seen in adults. Our patient is a 32-year-old pregnant female without significant past medical history, who presented to the emergency department with worsening abdominal pain and a large palpable abdominal mass. Imaging identified a large, hemorrhagic right hepatic lobe mass that in retrospect had imaging characteristics most suggestive of UES. Though extremely rare in adults, it is still important to recognize the imaging features of UES as to avoid mistaking it for other more common benign and malignant hepatic masses.