To investigate the clinical characteristics and prognosis of extracranial malignant rhabdoid tumor (eMRT) in children, and to provide a reference for the clinical treatment of this disease.

A retrospective analysis was performed on the clinical data of children with newly diagnosed eMRT who were admitted and treated in the Department of Pediatric Oncology, Beijing Children's Hospital Affiliated to Capital Medical University, from March 2009 to December 2024. The clinical characteristics were summarized, and survival analysis and prognostic risk factor analysis were conducted.

A total of 43 children with eMRT were included in this study, the median age at diagnosis of all patients was 20 months (range: 2-138 months). Among them, 24 cases were malignant renal rhabdoid tumors and 19 cases were extracranial, extrarenal rhabdoid tumors. Of the 43 children, 23 cases (53.5%) were complicated with distant metastasis. Twenty-nine (67.4%) underwent primary tumor resection. Among the children, 24 (55.8%) underwent gross total resection (GTR), 5 (11.6%) partial resection, and 14 (32.6%) biopsy only. Their 3-year overall survival (OS) rates were 40.8%, 35.3%, and 33.3%, respectively (P=0.711). Chemotherapy was administered to 42 children (97.7%); among those who were ineligible for GTR and had poor chemotherapy sensitivity, the 3-year OS rate was significantly lower than that of chemotherapy-sensitive children (28.6% vs. 58.2%, P=0.041). Radiotherapy was given to 15 children (34.9 %), with the 3-year OS rate in the radiotherapy group being higher than that in the non-radiotherapy group (69.1% vs. 32.9%, P=0.026). The 3-year event-free survival (EFS) and OS rates of all 43 children were 31.4% and 44.3%, respectively. Multivariate Cox regression analysis showed that a diagnostic age < 12 months was significantly associated with a higher risk of death (hazard ratio[HR]=3.7, 95% confidence interval[CI]: 1.2-11.1, P=0.020).

Children with eMRT have an overall poor prognosis. A diagnostic age < 12 months is an independent risk factor for higher mortality in these children. Further large-scale, long-term follow-up studies are needed to explore the prognostic factors of this disease.