Non-Rhabdomyosarcoma Soft Tissue Sarcoma

Soft tissue sarcomas develop from the supporting tissues of the body. Those that are not rhabdomyosarcoma are grouped together as non-rhabdomyosarcoma soft tissue sarcomas (NRSTS), but they include many distinct tumour types. Examples seen in children and adolescents include synovial sarcoma, infantile fibrosarcoma, malignant peripheral nerve sheath tumour, epithelioid sarcoma and desmoplastic small round cell tumour.

These tumours are more common in adolescents than in young children, with the exception of infantile fibrosarcoma, which occurs in babies and often behaves in a less aggressive way. Each type has its own pattern of behaviour, and some carry particular genetic changes that can influence treatment. Because they are rare, children are treated within a specialist children's cancer service with access to expert pathology review.

Most children present with a painless, enlarging lump, often in an arm or leg or on the trunk. Tumours deep in the abdomen or chest may cause pain, swelling or pressure symptoms before they are noticed. Any soft tissue lump that is growing, larger than a few centimetres, or deep to the muscle layer should be assessed carefully.

MRI is the preferred scan for defining the tumour and its relationship to muscles, nerves and blood vessels. A biopsy, usually a needle biopsy under imaging guidance or a small open biopsy, is performed to establish the exact type of sarcoma and its grade. This is planned by the surgeon so that the biopsy track can be removed at the definitive operation. A chest CT is performed to check the lungs, and additional scans are added depending on the tumour type.

Treatment is planned by a multidisciplinary children's cancer team and depends on the tumour type, its grade, its size and whether it can be completely removed. For many low-grade and small tumours, complete surgical removal is the main treatment and may be all that is required. Higher-grade or larger tumours are often treated with radiotherapy before or after surgery to reduce the chance of the tumour returning at the same site, and chemotherapy is used for some tumour types and where the disease has spread.

Some sarcomas carry specific genetic changes that can be targeted with newer medicines, and this is considered as part of the treatment plan. Your child's surgeon coordinates the timing of the operation with the oncologists so that any pre-operative treatment is completed before surgery.

The operation aims to remove the tumour completely with a margin of normal tissue around it, which offers the best chance of local control. The surgeon plans the incision to include the biopsy site and works from the MRI to protect important nerves and blood vessels. For limb tumours, the vast majority of children can be treated with limb-preserving surgery; amputation is rarely needed.

For tumours involving the chest or abdomen, the operation is planned together with other surgical specialties as required. If the pathology shows tumour close to or at the edge of the removed tissue, a further operation or radiotherapy may be recommended. The procedure is performed under general anaesthesia by a paediatric surgical team, and your child's surgeon will explain what is involved in their specific case.

Recovery depends on the site and size of the operation. Many children go home within a few days, with wound care, pain relief and activity advice provided by the treating team. Physiotherapy or occupational therapy is often arranged after limb surgery to restore strength and movement, and wounds in areas that will receive radiotherapy need to heal fully first.

The pathology report is reviewed at the multidisciplinary meeting to decide whether further treatment is needed. Follow-up includes regular clinical examination, MRI of the operated area and chest imaging over several years, since the lungs are the most common site of spread. Families are supported by the children's cancer service throughout, including through long-term follow-up clinics once treatment is complete.