Primary Bone Tumors

Question 1

Giant cell tumor (osteoclastoma)

Answer 1

Epidemiology/Location: 20-40 years of age. Epiphyseal end of long bones.
Characteristics: Locally aggressive benign tumor often around the distal femur, proximal tibial region (knee). “Double bubble” or “soap bubble” appearance on x-ray. Spindle-shaped cells with multinucleated giant cells.

Question 2

Osteochondroma (exostosis)

Answer 2

Epidemiology/Location: Most common benign tumor. Males < 25 years of age.
Characteristics: Mature bone with cartilaginous cap. Commonly originates from long metaphysis. Malignant transformation to chondrosarcoma is rare.

Question 3

Osteosarcoma (osteogenic sarcoma)

Answer 3

Epidemiology/Location: 2nd most common 1 degree malignant bone tumor (after multiple myeloma). Male > female, 10-20 years of age (1 degree). Prediposing factors: Paget’s disease of bone, bone infarcts, radiation, familial retinoblastoma. Metaphysis of long bones, often around distal femur, proximal tibial region (knee).
Characteristics: Codman’s triangle (from elevation of periosteum) or sunburst pattern on x-ray. Aggressive. Treat with surgical en bloc resection (with limb salvage) and chemotherapy.

Question 4

Ewing’s sarcoma

Answer 4

Epidemiology/Location: Boys < 15 years of age. Commonly appears in diaphysis of long bones, pelvis, scapula, and ribs.
Characteristics: Anaplastic small blue cell malignant tumor. Extremely aggressive with early metastases, but responsive to chemotherapy. “Onion skin” appearance in bone (“going out for Ewings and onion rings”). Associated with t(11;22) translocation. 11 + 22 = 33 (Patrick Ewing’s jersey number).

Question 5

Chondrosarcoma

Answer 5

Epidemiology/Location: Men 30-60 years of age. Usually located in pelvis, spine, scapula, humerus, tibia or femur.
Characteristics: Malignant cartilaginous tumor. May be of 1 degree origin or from osteochonfroma. Expansile glistening mass within the medullary cavity.