• 15% of all skin /subcutaneous tumors
  • STS of the trunk and extremities are very invasive into surrounding tissue with a generally low metastatic rate
  • Malignant peripheral nerve sheath tumor is most common soft tissue sarcoma
  • Complete, wide surgical resection, confirmed histologically, is highly predictive of local tumor cure
  • These tumors are not encapsulated but have a "pseudocapsule" comprised of compressed tumor cells
  • 40%-70% of grade 3 tumors will metastasize "Soft tissue sarcomas (STS) make up a large category of tumors that arise from connective tissue. This category includes tumors of fibrous tissue, fat, smooth muscle, nerves, and lymphatic vessels. Histologic diagnoses include fibrosarcoma, MPNST, malignant fibrous histiocytoma, myxosarcoma, liposarcoma, lymphangiosarcoma and undifferentiated sarcoma. The most common STS in dogs is the malignant peripheral nerve sheath tumor. Tumors such as hemangiosarcoma, osteosarcoma, chondrosarcoma, rhabdomyosarcoma and synovial cell sarcoma are often classified as soft tissue sarcomas. However, their behavior is not consistent with that of the more common STS and they are therefore considered separately in veterinary medicine."
  • tumors of the skim
    "Approximately 20 to 30% of primary tumors of the skin and subcutaneous tissues are histologically malignant in the dog, compared to 50 to 65% in the cat." This site EXCELLENT FOR CATS
  • GENERAL fact sheet for soft tissue sarcomas
    Soft tissue sarcomas (STS) are tumours arising from connective tissue (mesenchyme other than bone) in middle aged to old dogs. They comprise about 15% of all skin tumours, and about 1% of all malignancies. The most common histological types of STS are fibrosarcomas, haemangiopericytomas, neurofibrosarcomas, schwanomas (also called malignant peripheral nerve sheath tumors), and malignant fibrous histiocytomas. Excluded in this group are tumours of haematopoietic or lymphoid origin and haemangiosarcomas. Despite the different histological types, STS share similar characteristics:
  • arise from any anatomic site in the body
  • locally invasive
  • recur after conservative excision
  • low metastatic rate
  • poorly responsive to radiation therapy
    " What exactly do we mean when we make a diagnosis of soft tissue sarcoma? This includes a group of sarcomas including fibrosarcoma, peripheral nerve sheath tumors (schwannoma or neurofibrosarcoma), "hemangiopericytoma," malignant fibrous histiocytoma, myxosarcoma, and liposarcoma. With the possible exception of liposarcoma, the exact tumor type is less important than the grade of tumor. In fact, at the light microscope level, it is difficult to distinguish between schwannoma and neurofibrosarcoma, and hemangiopericytomas are likely a form of peripheral nerve tumor. The grading system we use is adopted from human medicine and comprises three grades -- 1 being the least malignant and 3 being the most malignant. Grade is based on overall tumor differentiation, mitotic rate, and amount of tumor necrosis. In a recent study of dogs with soft tissue sarcomas treated by aggressive surgery alone, grade was predictive of survival as the 3-year survival rate was about 80% for grade 1, 50% for grade 2, and 20% for dogs with grade 3 tumors (JAVMA 211; 1997, p. 1147). Grade also was predictive of tumor recurrence in soft tissue sarcomas treated with surgery and adjuvant radiation therapy.
    Hemangiosarcoma,Hemangiopericytomas and Hemangiomas
    for humans
    labbies sarcomas
    Tumors such as fibrosarcomas, neurofibrosarcomas (nerve sheath tumors), malignant fibrous histiocytomas, hemangiopericytomas, and myxosarcomas are referred to as soft tissue sarcomas. All tend to be solitary, invasive, subcutaneous masses occurring in middle aged or old animals. Most are relatively slow to spread, but frequently recur after local excision. The tissue of origin of some sarcomas may be difficult to discern, so the diagnosis of undifferentiated sarcoma is made..... The rate of growth is variable, but time from surgical removal to recurrence ranges one or two weeks to than a year later. Cats with surgical margins free of tumor had a median time to recurrence of 16 months, whereas in those with "dirty" margins, the median time to recurrence was 4 months, and their median survival was only 9 months.