Undifferentiated sarcoma of the liver.

Undifferentiated sarcoma of the liver (USL) is one of the rare malignant liver tumors of mesenchymal origin in children and adolescents. USL is difficult to diagnose in its early stages and sometimes the tumor ruptures. We present the case of a 13-year-old boy with USL that ruptured because of abdominal trauma. This was initially diagnosed as a post-traumatic hematoma. A brief review of USL and its treatment principles are discussed.