Briefly mention classification of bone tumours.

Classification of Bone Tumors

Bone tumors are broadly classified into primary and secondary tumors.

1. Primary Bone Tumors

These tumors originate within the bone tissue itself. They are further categorized based on the tissue of origin.

• Osteogenic Tumors (Bone-forming): These tumors produce osteoid, the matrix of bone.
  • Osteoma: Benign, slow-growing, often found on the skull.
  • Osteoid Osteoma: Benign, small, painful, typically in the long bones.
  • Osteoblastoma: Benign, larger than osteoid osteoma, can be more aggressive.
  • Osteosarcoma: Malignant, most common primary bone cancer, often affecting adolescents and young adults, typically in the metaphysis of long bones.
• Chondrogenic Tumors (Cartilage-forming): These tumors produce cartilage.
  • Chondroma: Benign, common, often found in the small bones of the hands and feet.
  • Osteochondroma: Benign, most common bone tumor overall, characterized by a bony outgrowth covered with cartilage.
  • Chondroblastoma: Benign, typically found in the epiphysis of long bones, affecting young adults.
  • Chondrosarcoma: Malignant, second most common primary bone cancer, typically affecting older adults, often in the pelvis, femur, and humerus.
• Fibrogenic Tumors (Fibrous tissue-forming): These tumors arise from fibrous tissue.
  • Fibrous Dysplasia: Benign, developmental abnormality where normal bone is replaced by fibrous tissue.
  • Non-ossifying Fibroma: Benign, common, often found in the metaphysis of long bones, usually asymptomatic.
  • Fibrosarcoma: Malignant, rare, aggressive tumor arising from fibrous tissue.
• Other Primary Bone Tumors:
  • Giant Cell Tumor (GCT): Locally aggressive, typically found near the epiphysis of long bones, affecting young adults.
  • Ewing Sarcoma: Malignant, highly aggressive, typically affecting children and young adults, often in the diaphysis of long bones.

2. Secondary Bone Tumors (Metastatic Bone Tumors)

These tumors originate from cancers elsewhere in the body and spread to the bone. They are far more common than primary bone tumors.

• Common primary sites include: Breast, Lung, Prostate, Kidney, Thyroid.
• Metastases often affect the axial skeleton (spine, pelvis, ribs) due to rich blood supply.
• Symptoms include pain, pathological fractures, and hypercalcemia.

The following table summarizes the classification:

Tumor Type	Origin	Benign/Malignant	Common Location
Osteosarcoma	Bone	Malignant	Metaphysis of long bones
Chondrosarcoma	Cartilage	Malignant	Pelvis, femur, humerus
Osteoma	Bone	Benign	Skull
Chondroma	Cartilage	Benign	Small bones of hands/feet
Ewing Sarcoma	Unknown	Malignant	Diaphysis of long bones
Metastatic Cancer	Various	Malignant	Axial Skeleton