Undifferentiated embryonal sarcoma of the liver in children: our experience in four difficult cases and three-dimensional practical exploration.

Aims: To explore rare and difficult cases of undifferentiated embryonal sarcoma of the liver (UESL) in children in a single centre, summarize the diagnosis and treatment experience and analyse the role of a computer-assisted surgery system (Hisense CAS), thus providing a new global vision and three-dimensional perspective.

Methods: We retrospectively collected the clinical data including the diagnoses and treatment processes, of children with UESL confirmed by histopathological examination in our hospital from January 2009 to December 2020. The relationship between the tumour volume and important blood vessels and between the liver volume and tumour volume, as well as other three-dimensional characteristics in the reconstructed three-dimensional model were analysed using Hisense CAS. The findings from this analysis can be used to aid in surgical decision-making and preoperative planning.

Results: Four children-3 girls and 1 boy-with UESL were included in the study. The age at onset ranged from 6 to 8 years. All four children presented with symptoms of abdominal discomfort, and abdominal masses were detected during physical examination. Owing to the wishes of their parents and the possibility that the disease was benign, all four children underwent one-stage radical surgery. For patient 1, a three-dimensional reconstruction was created during the initial diagnosis, which made accurate evaluation and planning of the preoperative procedure challenging. In patient 2, the tumour was located in the middle lobe of the liver and involved the first and second hepatic hilum. For patient 3, the pathological diagnosis of the tumour after surgery was challenging, but eventually, the diagnosis was confirmed through histochemistry and consultation with higher-level hospitals. Patient 4 had a giant tumour, which had a preoperative simulated future liver remnant volume (FLV) that was 21.0% of the total volume of the liver and tumour (TLTV). According to the standard liver volume (SLV) for children, the FLV was 77.0% of the SLV, making surgery feasible. All four children underwent complete resection, and only patient 4 experienced recurrence below the diaphragm 19 months after surgery. Currently, the 3-year overall survival rate is 100%, and the 3-year event-free survival rate is 75%.

Conclusion: UESL in children is rare, and the key to diagnosis and treatment is complete surgical resection. Through individualized three-dimensional surgical planning, accurate and complete resection of difficult and complex UESL in children can be achieved, leading to a favourable prognosis.