Undifferentiated embryonal sarcoma of the liver with an unusual presentation: case report and review of the literature.

Undifferentiated embryonal sarcoma of the liver (UESL) is a rare malignant mesenchymal neoplasm, relatively unique to the liver that occurs primarily in children and teenagers. Delay in diagnosis is not uncommon due to lack of a characteristic clinical presentation, serological markers and radiological changes. We report a case of UESL in a 9-year-old girl who presented with right upper quadrant pain and a palpable mass. Laboratory and imaging workup revealed a complex hepatic cyst, increased IgE, transient peripheral eosinophilia and a normal alpha-fetoprotein (AFP). Initial empirical treatment with albendazole was implemented for presumed hydatid cyst disease, but the child failed to improve. Subsequent surgical resection resulted in the correct diagnosis of UESL. She received 6 months of chemotherapy and remains well with no evidence of tumor about 12 months after resection. We herein review the typical clinical, radiologic and pathologic features of this rare tumor.