Epidemiology

Know the who, what and where of bone and soft tissue tumours and you will be a lot closer to making a diagnosis and a plan for investigations. Tumour simply means a growth. Tumours can be benign, in which case they stay localized; or malignant, in which case they can spread to other sites. Tumours can be found in the bone and soft tissues because they arose there primarily or because they metastasized there from other sites.

Primary bone and soft tissue tumours are a large and heterogeneous group of neoplasms, and we can get some guidance about what might be the diagnosis by knowing some of their predilections. Ultimately sarcomas can affect anyone, anywhere, anytime, and the differential diagnosis of a single lump can still be broad. However, a painful, swollen distal thigh with a destructive lesion on the X-ray is more likely to be a primary bone sarcoma in a child, and more likely to be a metastatic lesion in an elderly patient.

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Overview

  • Heterogeneous group of neoplasms; many subtypes
  • Benign tumours are far more common
  • Malignant tumours are generally known as sarcomas
    • Account for 1-2% of all human malignancies

Age Distribution

  • All age groups are affected, some tumours show a strong age predilection
    • Embryonal rhabdomyosarcoma - children
    • Synovial sarcoma - young adults
    • Pleomorphic undifferentiated sarcoma - older patients
  • Sarcomas account for 10 to 15% of all malignancies in the <25 age group
  • Bone sarcomas have a bimodal age distribution

Risk Factors

Most sarcomas occur sporadically, but some are associated with well-established risk factors.

  • Ionizing Radiation
  • Viral infection - Kaposi Sarcoma, smooth muscle tumours
  • Paget’s disease and chronic osteomyelitis - Osteosarcoma
  • Rare genetic disorders - Li-Fraumeni syndrome

Location

  • Soft tissue sarcomas can occur anywhere
    • Extremities most common
    • Retroperitoneal tumours can get quite large and are difficult to treat
    • Visceral organs such as the gastrointestinal tract and uterus
  • Bone sarcomas can occur in appendicular and axial skeleton
    • Most common in areas of high growth, e.g. distal femur, proximal tibia, proximal humerus
    • Spinal and cranial tumours are very challenging to treat