A single-center retrospective study of malignant ectomesenchymoma in children.

Objectives: This study aimed to summarize the clinical and pathological characteristics of Malignant Ectomesenchymoma (MEM) and provide an overview of the available treatment options.

Methods: A retrospective analysis was conducted on data from 11 children diagnosed with MEM at Beijing Children's Hospital between 2012 and 2023.

Results: The study included nine male and two female patients, with a median age of 3 years (range, 1.5-11.0 years). The most commonly affected sites were the head and neck (45.6%), followed by the limbs (27.2%) and the pelvis/abdomen (27.2%). Nine children presented with localized MEM, while two had metastatic disease at the time of diagnosis. Among the nine children who underwent surgery, four received a combination of radiotherapy and chemotherapy, while five were treated with chemotherapy alone. Two children received only conservative treatment. The median follow-up period was 5.8 years (range, 0.7-12.3 years). Children who received both radiotherapy and chemotherapy had a significantly lower relapse rate compared to those treated with chemotherapy alone (2/6 vs. 5/5, P = 0.046). Additionally, children with FOXO1(+) tumors had lower survival rates than those with FOXO1(-) tumors (0/2 vs. 7/8). The 5-year overall survival rate was 79%, while the event-free survival rate was 14%.

Conclusions: Combining chemotherapy with local treatments such as surgery and radiotherapy can improve the prognosis for children with MEM. Radiotherapy may be beneficial in reducing the incidence of adverse effects in patients with MEM.