Commonest sarcoma in children is -
Rhabdomyosarcoma

Commonest sarcoma in children is rhabdomyosarcoma.
It is a tumour of Primitive mesodermal origin.
The most common site is head and neck.
The genitourinary region is the second most common site.
Other sites are extremities and retroperitoneum
Rhabdomyosarcoma
Lipoma
Angiosarcoma
Fibrosarcoma