Sarcomas are rare neoplasms arising from connective tissue elements of the body. Approximately 80% arise in soft tissue, while the remainder originate in bone. 1 Soft-tissue sarcomas are tumors of the mesenchymal system, and about half develop in the extremities. Bone sarcomas are characterized by their location in bone and sometimes produce osteoid, or immature bone.
The most common types of soft-tissue sarcomas are malignant fibrous histiocytoma (although this term has lost favor with some pathologists) and liposarcoma.
The most common types of bone sarcomas are osteosarcoma (a sarcoma that makes osteoid or bone), Ewing sarcoma (composed of small round blue cells with a characteristic chromosomal translocation), and chondrosarcoma (a sarcoma that makes chondroid tissue, or cartilage).
EPIDEMIOLOGY AND PRIMARY BODY SITES
Approximately 10,600 new cases of soft-tissue sarcoma and 2,570 new cases of bone sarcoma were estimated to have been diagnosed in the United States in 2009. 2,3 For perspective, the annual incidence of soft-tissue sarcoma is approximately 5.5% that of breast cancer and approximately 5% that of lung cancer. 3
Most sarcomas develop in the lower extremities, although the age groups at greatest risk vary among sarcoma types. 4
Soft-tissue sarcomas develop most commonly in the thigh and occur primarily in adults. 2
Osteosarcomas are the most common bone sarcoma and develop most frequently in 10- to 20-year-olds; their most common location is the distal femur. 5–8 Metastatic osteosarcoma is found in approximately 20% of patients at the time of osteosarcoma diagnosis. Osteosarcomas mainly spread hematogenously, and the lungs are the most common initial site of metastases, being affected in up to 90% of patients with metastatic disease. 9
Ewing sarcomas develop most often in the long bones of the extremities or bones of the pelvis. The large majority of cases develop in patients aged 10 to 15 years. 5–8
Chondrosarcomas represent approximately 20% of all bone sarcomas and primarily affect older adults, with a peak incidence in the sixth decade of life. 10
OVERVIEW OF PRESENTATION AND EVALUATION
Presentation is highly variable
The clinical presentation of patients with bone or soft-tissue sarcoma is highly variable. Patients often present with a mass, typically one that is increasing in size. In general, bone sarcomas are painful and soft-tissue sarcomas are not, but there are exceptions to this general rule. Constitutional symptoms are rare in patients with bone or soft-tissue sarcomas, but symptoms such as fever, malaise, and weight loss can be seen, especially in patients with Ewing sarcoma. 11
Delayed presentation and diagnosis are common
Particularly when a sarcoma is painless, patients sometimes do not seek medical attention until a suspicious mass becomes quite large. Certain tumors, such as synovial sarcoma, a high-grade soft-tissue sarcoma often seen in young adults, may present as a slowly growing or stable-appearing mass over several years. In one study of 33 children with synovial sarcoma, the mean duration of symptoms was 98 weeks (range, 2–364), the mean patient delay before a doctor was seen was 43 weeks (0–156), the mean doctor delay before a correct diagnosis was made was 50 weeks (0–362), and the mean number of doctors seen before referral was 3 (1–6). 12 For nearly half the patients in this study (15), the diagnosis was obtained only after unplanned excision, meaning that the surgeon did not expect a malignancy at the time of biopsy. Because delayed presentation is not uncommon in cases of bone or soft-tissue sarcoma, every patient with a mass with indeterminate imaging findings should be referred to or reviewed by an orthopedic or musculoskeletal oncologist.