[Clinical and imaging features of abdominal rhabdomyosarcoma of non-organ origin in children].

Objective: To evaluate the clinical and imaging features of abdominal rhabdomyosarcoma of non-organ origin in children. Methods: We retrospectively analyzed the clinical and imaging features of 12 pediatric patients with abdominal rhabdomyosarcoma confirmed by surgery and pathology at our hospital. Results: There were 9 boys and 3 girls, with an average age of (5.47±3.92) years old (range, 1 to 15). According to Intergroup Rhabdomyosarcoma Study (IRS) staging system, they were of stage Ⅲ to stage Ⅳ, and most were of embryonal type. Tumors of 7 cases were located in the pelvic cavity, 2 cases in the abdominal cavity, 1 in the retroperitoneal space, 1 in both the abdominal and pelvic cavities and 1 across the retroperitoneal space, and abdominal and pelvic cavities. Gray-scale ultrasound showed moderate inhomogeneous echo structure and color Doppler flow imaging showed rich blood flow signals. CT plain scan showed masses of iso- or low-density, and the contrast-enhanced scan showed lesions with inhomogeneous enhancement. The enhancement in delay scan was more obvious and the peripheral enhancement was more significant than central enhancement. Conclusions: Childhood abdominal rhabdomyosarcoma of non-organ origin may arise from the peritoneum, be commonly seen in boys younger than 10 years old, more likely located in the pelvic cavity, and embryonal rhabdomyosarcoma is the most common histological variant seen in childhood. Ultrasound and CT imaging can provide useful information for diagnosis and differential diagnosis of this tumor.