Sarcomas are malignant tumors of mesenchymal origin.
Mesenchyme = embryonic connective tissue derived from the mesoderm.
The mesoderm differentiates into hematopoietic and connective tissue.
Sarcomas arise from the skeleton and "supporting structures":
- Skeletal (voluntary muscle)
- Smooth (involuntary muscle)
- Fibrous tissue
There are many different types of sarcomas with a broad range of histological appearances, differentiation and clinical behaviors.
Sarcomas can be classified in terms of their location:
- Soft tissue
Soft tissue Sarcomas (STS) :
Childhood muscle sarcomas are broadly grouped as:
- Rhabdomyosarcoma (RMS)
- Non-rhabdomyosarcoma soft tissue sarcoma (NRMS, Non-RMS or NRMSTS)
Rhabdomyosarcomas (RMS) are thought to arise from immature mesenchymal cells that should normally be involved in the development of skeletal muscle. But RMS can be found in areas where one would not expect to find striated muscle.
In Canada, between 2000 and 2004, rhabdomyosarcoma had a 5 year OSP (Observed Survival Proportions) for children between 0 and 14 years of 80%.
Non-Rhabdomyosarcoma tumors (Non-RMS) include:
- Liposarcomas (rare)
- Lipoblastoma (rare)
- Epithelioid sarcoma
- Synovial sarcoma
- Infantile fibrosarcoma
- Pleomorphic sarcoma (formerly called malignant fibrous histiocytoma)
- Alveolar soft part sarcoma
- Clear cell sarcoma of the soft tissues
- Peripheral nerve sheath tumor
The most common bone tumors in children are:
- Osteogenic sarcoma
- Ewing sarcoma
In Canada between 2000 and 2004 bone sarcomas had one of the lowest 5 year OSP (Observed Survival Proportions) of any childhood cancer diagnosed between 0 and 14 years. It was 66%.