Congenital soft tissue Ewing's sarcoma A case report of pre- and postnatal magnetic resonance imaging findings

Rationale: Most congenital soft tissue masses are benign. Ewing's sarcoma (ES) is a highly malignant tumor that commonly occurs in children and adolescents and rarely occurs during the fetal period. Cases of congenital soft tissue ES with magnetic resonance imaging (MRI) findings are scarce. To the best of our knowledge, no previous reports have described the pre- and postnatal MRI findings of ES. Patient concerns: We present a case of congenital soft tissue ES arising in the body wall, which was examined using MRI during the prenatal and neonatal periods. Diagnoses: Malignancy was suspected by diffusion-weighted imaging, which demonstrated restricted diffusion within the mass even during the fetal period. ES was confirmed via histopathological examination after birth. Interventions: The patient initially underwent conservative treatment for suspected hemangioma. Tumorrectomy was undergone after three weeks based on previously dissatisfied therapeutic effects. Outcomes: The patient died of multiple distant metastases despite undergoing postoperative chemotherapy and metastasectomies. Lessons: Fetal or neonatal soft tissue ES may be clinically misdiagnosed as a hemangioma. It is important to suspect this through an imaging approach such as diffusion-weighted imaging.