MSK Neoplastic Disorders

Question 1

Osteosarcoma

Answer 1

• Definition:
  
  • malignant tumor of osteoblastic proliferation: Most common primary malignant tumor of bone
• Location:
  
  • metaphysis of long bones near physeal plates. Distal femur = most common, proximal tibia, humerus
• Epidemiology:
  
  • rate (~1000 new cases/ year with 450/year in children) most common form of bone cancer in children, bimodal = first peak is age 10-30yo, second peak is >60 yo.
• Risks:
  
  • prior radiation, Paget’s disease, males
• S/sxs;
  
  • Localized bone pain that may be worse at night
  • -Joint swelling
  • -Palpable soft tissue mass
• Dx:
  
  • Xray: “Sunburst” or “hair on end” appearance d/t spicules of calcified bone radiating in right angles
  • Biopsy = definitive dx
• Tx:
  
  • Malignant
  • *Aggressive management: limb salvage surgery + chemo/radiation

Question 2

Chondrosarcoma

Answer 2

• Definition:
  
  • cancer of the cartilage
• Location:
  
  • femur, rib, iliac bone, humerus, tibia
• Epidemiology:
  
  • adults 40-75 yo
• S/sxs:
  
  • Localized pain & swelling
• Dx:
  
  • XR:
    
    • Low grade: well-defined osteolytic chondroid matrix & scalloping
    • -High grade: large lesion with extension into soft tissues
  • “Popcorn mineralization” described as ring & arc appearance
• Tx:
  
  • Malignant but less aggressive & more slow growing than osteosarcoma with less potential for mets (better prognosis)
  • Surgical resection &/or chemo

Question 3

Ewing’s Sarcoma

Answer 3

• Definition:
  
  • malignant tumor of the bone that may metastasize
• Location:
  
  • diaphysis of long bones. Femur = most common, pelvis, tibia, fibula
• Epidemiology:
  
  • 2nd most common primary bone malignancy in children (after osteosarcoma)
• S/sxs:
  
  • Localized bone pain & swelling
  • Systemic symptoms: fever, weight loss, malaise (mimics infection)
• Dx:
  
  • Xray: layered periosteal reaction “onion skin” appearance
  • -Lytic lesions with a “moth eaten” appearance
  • Bone marrow biopsy
• Tx:
  
  • Malignant
  • surgery, chemo, radiation
  • *5-years survival rates: local = 70%, metastatic = 15-30%

Question 4

Osteochondroma

Answer 4

• Definition:
  
  • cartilage-capped bony overgrowth arising on the external surface of a bone & areas of tendon insertion. MC benign bone tumor
• Location:
  
  • only develops in bones of endochondral origin at the metaphysis near the growth plate of long bones
• Epidemiology:
  
  • begins in childhood (10-20yo males), & grows until skeletal maturity (closure of growth plates)
• S/sxs:
  
  • *Usually an incidental finding, but can be painful if impinges on a nerve or stalk is fractured
• Dx:
  
  • XRAY: -Pedunculated, growing away from the growth plate
  • Biopsy = definitive
• Tx:
  
  • Benign
  • Asymptomatic: observation (repeat films every few years)
  • -painful: marginal resection
• Complications:
  
  • Malignant transformation is rare but occurs more frequently in multiple hereditary osteochondromas

Question 5

Osteoid Osteoma

Answer 5

• Definition:
  
  • benign bone tumor characterized by a small radiolucent nidus (<15mm in diamter)
• Location:
  
  • 50% occur in the long bones of the lower extremities, posterior elements of the spine
• Epidemiology:
  
  • most commonly presents in 2nd decade
• S/sxs:
  
  • Progressively increasing pain that is worse at night & unrelated to activity
  • pain relieved within 20-25 minutes of NSAID/ASA
• Dx:
  
  • Xray: small round lucency (nidus) with a sclerotic margin
• Tx:
  
  • Benign
  • NSAIDs/ASA
  • Continued pain: CT guided percutaneous radiofrequency ablation (>90% effective)

Question 6

Aneurysmal Bone Cyst

Answer 6

• Definition: benign pediatric blood-filled bone tumor
• Location:
  
  • occurs at metaphysis of long bones
• Etiology:
  
  • median age of 13yo (rare after 30yo)
• S/sxs:
  
  • painful swelling
• Dx:
  
  • XRAY: Eccentric metaphyseal lucent lesion with a thin sclerotic margin & fine internal septum
  • Biopsy = necessary for Dx
• Tx:
  
  • Benign
  • Surgery
• Complications:
  
  • pathologic fractures: especially if size of the tumpe is approaching >50% of the bone volume

Question 7

Osteoblastoma

Answer 7

• Definition:
  
  • rare benign bone tumor ( >1.5cm (large))
• Location:
  
  • spinal column (40%) usually involving the posterior column-specifically the cervical spine or sacrum. Metaphysis & distal diaphysis of the long bones
• Epidemiology:
  
  • Presents in 20-30yo,male = more common
• Forms:
  
  • conventional, aggressive
• S/sxs:
  
  • Persistent back pain
• Dx:
  
  • Xray: may look like ABC or large osteoid osteoma
  • Ranges from lytic to densely sclerotic
• Tx:
  
  • Benign
  • Refer to oncology
• Complications:
  
  • Risk of malignant transformation to osteosarcoma

Question 8

Where do secondary bone tumors most often spread to>

Answer 8

PT Barnum Loves Kids

• P: prostate, parathyroid
• T: thyroid
• B: breast, brain
• L: lungs, liver
• K: kidney