Undifferentiated Embryonal Sarcoma of the Liver in Pediatrics: A Diagnostic Challenge With Implications for Early Management.

A 10-year-old boy was evaluated for intermittent colicky abdominal pain, general malaise, and asthenia. Imaging revealed a solid liver lesion. Subsequent biopsy and extension studies diagnosed the lesion as undifferentiated embryonal sarcoma of the liver, classified as PRETEXT II, group III according to the postoperative staging system of the Intergroup Study for Soft Tissue Sarcomas. He underwent neoadjuvant chemotherapy using alternating cycles of ifosfamide, doxorubicin, vincristine, D-actinomycin, and cyclophosphamide. This was followed by surgical intervention and two additional adjuvant chemotherapy cycles, resulting in a complete disease response. The patient remains in follow-up and shows no signs of relapse 28 months post-diagnosis. Undifferentiated embryonal sarcoma of the liver is a rare and often misdiagnosed condition that can be mistaken for a benign disease. Its prognosis hinges on timely and accurate diagnosis, which is essential for effectively treating patients with this aggressive pathology with a high mortality risk. Notably, there is no standard treatment approach. In our case, we implemented therapeutic strategies from various literature reports, yielding a promising outcome and positive patient progression.