Primary Bone Tumors First Aid Page 389

Question 1

Benign Bone Tumors

Answer 1

• Giant Cell Tumor (osteoclastoma), Osteochondroma (exostosis)

Question 2

Malignant Bone Tumors

Answer 2

• Osteosarcoma, Ewing’s Sarcoma, Chondrosarcoma

Question 3

Giant Cell Tumor Epidemiology/Location

Answer 3

• 20-40 years of age at the Epiphyseal end of long bones.

Question 4

Giant Cell Tumor Characteristics

Answer 4

• Locally aggressive, often around the distal femur or proximal tibia (KNEE).
• “Double Bubble” or “Soap Bubble” appearance on x-ray.
• Spindle-shaped cells with multinucleated giant cells.

Question 5

Osteochondroma Epidemiology/Location

Answer 5

• Most common benign tumor. Males <25 years.
• Lateral projection of growth plate (metaphysis) due to LOF mutations in EXT1 or EXT2 which decreases Heparan Sulfate Proteoglycan production = defective endochondral ossification.

Question 6

Osteochondroma Characteristics

Answer 6

• Mature bone with cartilaginous cap that commonly originates from long metaphysis.
• Malignant transformation to chondrosarcoma is rare.

Question 7

Osteosarcoma Epidemiology/Location

Answer 7

• 2nd most common malignant bone tumor (osteoblasts) after multiple myeloma, Males 10-20 years of age.
• Predisposing Factors: Paget’s Disease of Bone, bone infarcts, radiation, familial retinoblastoma.
• Metaphysis of long bones, often around distal femur or proximal tibia (KNEE).

Question 8

Osteosarcoma Characteristics

Answer 8

• Codman’s triangle (elevation of periosteum) and sunburst pattern on x-ray.
• Aggressive, treated surgically and with chemotherapy.
• Histo: Pleiomorphic cells producing osteoid in a coarse, lace-like pattern.

Question 9

Ewing’s Sarcoma Epidemiology/Location

Answer 9

• Boys <15 years in the diaphysis of long bones, pelvis, scapula, and ribs.

Question 10

Ewing’s Sarcoma Characteristics

Answer 10

• t(11:22) translocation - 11 + 22 = 33 (Patrick Ewing’s jersey number)
• “Onion skin” appearance in bone (going out for Ewing’s and Onion rings)
• Extremely aggressive with early metastases, but responds to chemo.
• Anaplastic small blue cell malignant tumor derived from poorly differentiated cells (NEURAL ECTODERM) and Homer-Wright Pseudorosettes).

Question 11

Chondrosarcoma Epidemiology/Location

Answer 11

• Men 30-60 years, usually in pelvis, spine, scapula, humerus, tibia, or femur. (Pathoma said small bones of hands/feet)

Question 12

Chondrosarcoma Characteristics

Answer 12

• Malignant cartilaginous tumor that may be of primary origin or from osteochondroma.
• Expansile glistening mass within the medullary cavity.