Sarcoma and connective tissue tumours arise from embryonic mesenchymal cells that have the capacity to mature into striated skeletal and smooth muscle, adipose and fibrous tissue, bone and cartilage among other tissues.
Neoplasms arising from neuroectodermal tissue that give rise to malignant tumours affecting peripheral nerves are also included because of similarities in clinical behaviour, management and outcome.
Soft tissue tumours may be benign or malignant. Malignant mesenchymal neoplasms comprise less than 1% of all adult malignancies and 15% of pediatric cancers. Approximately 80% of sarcomas originate from soft tissue and the rest originate from bone.
The group of soft tissue neoplasms includes more than 50 different histologic subtypes (more than 100 including benign neoplasms). WHO classifies most soft tissue neoplasms according to the presumptive tissue of origin.
Some examples include:
- Leiomyosarcoma, Liposarcoma, Fibrosarcoma, Angiosarcoma, Rhabdomyosarcoma, Malignant peripheral nerve sheath tumour (MPNST)
Where histogenesis is uncertain, the designation reflects the architectural pattern.
Some examples include:
- Alveolar soft part sarcoma, clear cell sarcoma, epithelioid sarcoma, Synovial sarcoma
Some connective tissue tumours do not (or rarely) metastasize but can be locally aggressive. Some examples include:
- Desmoid fibromatosis, Giant cell tumour of bone (GCTB), diffuse-type pigmented villonodular synovitis (dtPVNS).
References
Fletcher CDM, Bridge JA, Hogendoorn PCW, Mertens F. WHO classification of tumours of soft tissue and bone, 4th ed, IARC Press, Lyon 2013