2025 – PAGE 276 – HEMATOLOGY & ONCOLOGY

BONE TUMORS

LONG BONE TUMORS

PEARL: The definition of a long bone is one that is longer than it is wide. Therefore, the phalanges count. For the pediatric exam, you will likely be given images of only the following bones for this section: Humerus, Radius, Ulna, Femur, Tibia, and Fibula.

OSTEOGENIC SARCOMA & EWING’S SARCOMA (AKA EWING SARCOMA)

Osteogenic sarcoma and Ewing’s sarcoma (AKA Ewing sarcoma) are both malignancies of LONG BONES. They can metastasize (look especially for lung metastases). Treatment requires chemotherapy, radiation, and surgery.

• MNEMONIC: Imagine a child with a large bony tumor of the humerus extending out perpendicularly from his arm. He’s competing in a Special Olympics race. He starts off well, but with each step closer to the finish line his bony arm tumor is punching HOLES IN HIS LUNGS and limiting his breathing (metastasizes to lungs).
• OSTEOGENIC SARCOMA (AKA OSTEOSARCOMA): This is usually at the proximal or distal aspect of the long bones. Look for a long bone with a SUNBURST PATTERN/LESION.
  • PEARLS: This may present as a teen going through a GROWTH SPURT and having UNILATERAL bone pain (GROWING PAINS should be bilateral, at night, better with NSAIDS and without edema). It may also present as post-traumatic pain that actually gets worse instead of getting better.
  • IMAGE: www.pbrlinks.com/OSTEOSARCOMA1
  • IMAGE: www.pbrlinks.com/OSTEOSARCOMA2
• EWING SARCOMA: Look for a long bone with lamellated “ONION SKIN” lesions. These lesions look like a very thin extra layer of bone, or like a thin onion peel lying over the bone. They can also have a SUNBURST pattern similar to osteogenic sarcomas. Ewing sarcoma may affect the pelvic bones and soft tissues as well. Lesions are extremely painful.
• • IMAGE: www.pbrlinks.com/EWINGSARCOMA1 – White arrows point to ONION SKIN lesions, the red circle shows a SUNBURST pattern, and the blue circle shows an osteolytic lesion.
  • IMAGE: www.pbrlinks.com/EWINGSARCOMA2
  • IMAGE: Proximal Humerus – www.pbrlinks.com/EWINGSARCOMA3
  • IMAGE: Onion skin lesion. Bottom arrow – www.pbrlinks.com/EWINGSARCOMA4
  • MNEMONIC: U-WING’s sarcoma. U looks like two LONG BONES next to each other.

OSTEOCHONDROMA

Osteochondroma is a very common and BENIGN bony tumor that is usually PAINLESS and located near GROWTH PLATES. The bony tumor has a cartilaginous cap. No treatment is needed.

IMAGE: www.pbrlinks.com/OSTEOCHONDROMA1
IMAGE: www.pbrlinks.com/OSTEOCHONDROMA2

OSTEOID OSTEOMA

The osteoid osteoma description sounds a lot like “growing pains.” It is BENIGN, worse at night, and RELIEVED BY NSAIDS. The distinguishing feature is that it is UNILATERAL. X-rays will show a central radiolucency with thickened bone around it.

IMAGE: www.pbrlinks.com/OSTEOIDOSTEOMA1 (thickened bone)
IMAGE: www.pbrlinks.com/OSTEOIDOSTEOMA2 (central radiolucency)

PEARL/SHORTCUT: Nighttime pain is all gOOd! It’s either a benign osteoid osteoma (if unilateral) or growing pains (bilateral). OO = Osteoid Osteoma.

MNEMONIC:

• • osteogenic Sarcoma – S – Sunburst
  • osteoChondroma – C – Cartilaginous Cap
  • Osteoid Osteoma – OO – Owl’s eyes à sclerotic bone
  • Ewing’s Sarcoma – onion skin lesions which make your eyes hurt (painful lesions)