Undifferentiated Embryonal Sarcoma of the Liver in an Adolescent with Mesocolon Involvement Mimicking a Colon Tumor with Liver Invasion

Undifferentiated embryonal sarcoma (UES) of the liver is an uncommon and highly malignant tumor of mesenchymal origin. It almost exclusively occurs in childhood with a peak incidence between 6-10 years of age but rare occurrences in adults have also been reported. The synonym was first described by Stocker and Ishak in 1978 as a distinct clinicopathologic entity. In reviews of pediatric liver tumor, UES was found to be the third most common malignant liver tumor accounting for 13% of hepatic malignancy. UES patients often show nonspecific symptoms including fever, abdominal pain, and RUQ palpable mass with normal laboratory study and no reliable tumor marker has been confirmed. Imaging study often reveals large, heterogenous, and hypovascular lesion. Tumors are thought to be aggressive with very poor prognosis initially but long term survival following complete resection with neo- and/or adjuvant chemotherapy has been reported in recent years. We report a case of UES with invasion to mesocolon in an 18-year-old young adult who was treated at our institution with combined liver resection and right hemicolectomy.