We all know that when you “hear hoofbeats, think of horses” and when you “see stripes, think of zebras.”  Unfortunately, the horses and zebras often look similar.  While tachypnea is most often due to a viral process like Bronchiolitis, or a Pneumonia, we must stay vigilant for it being one of those Subtle Signs of Heart Failure.  Keeping a keen eye and ear on alert for these zebras is part of what our job demands.  A child presenting with Back Pain should catch your attention just like a the child complaining of persistent leg pain.  While it is most likely innocuous, it could also be a zebra getting ready to stampede: Osteosarcoma.


Osteosarcoma: Basics

  • In the USA, cancer is the second leading cause of death in children.
    • Leukemia leads all other cancers – ~50 per 1,000,000 (CDC Stats)
    • Osteosarcoma incidence – ~5 per 1,000,000 (CDC Stats)
  • Osteosarcoma is the most common primary bone tumor in patients < 40 years of age. (Haddox, 2015)
    • Other important primary bone tumors = Ewing and Chondrosarcomas
  • High rates of metastasis.
  • Vast majority of osteosarcomas in children are High Grade. (Gorlick, 2010)
  • Survival has improved with advances in surgical, chemotherapeutic, and radiation care.
    • Before 1970’s, 5-year survival was < 20%.
    • Now it approaches 70%.
    • Generally, children have a better prognosis compared to patients 18-40 years of age. (Haddox, 2015)


Osteosarcoma: Presentation

  • Peak frequency = onset of puberty
  • Location:
    • Most arise in the intramedullary space of the metaphysis. (Gorlick, 2010)
      • Most often in the long bones of the lower extremities.
      • ~50% involve the knee (Distal Femur and Proximal Tibia)
      • Proximal Humerus is next most common site.
    • Possible relationship with Growth Plates.
    • In older pts, it is more common in the axial skeleton.
      • Spine involvement only in 4-5% of cases.
  • Primary complaint = Pain.
    • Often insidious
    • Pain with activity is most common complaint.
      • Just like everything else that hurts… it hurts more when you use it.
      • Growing Pains” is often the original misdiagnosis.
    • May present with limp due to pain.
    • Larger lesions may present with palpable mass.
    • Uncommon to have night sweats, fever, or other systemic symptoms initially.
    • Pathologic Fracture (Lee, 2013)
      • Can cause the initial presentation (5 – 12%)
      • Can also develop during treatment
      • Associated with poorer prognosis.
  • Appearance on Radiographs
    • Lytic and blastic bone lesion
    • “Sunburst” appearance
    • Periosteal elevation related to soft tissue mass producing “Codman’s Triangle.” (Gorlick, 2010)
  • Metastasizes to the Lungs and other Bones primarily.


So the next time you see the pre-teen who is complaining of knee pain after running in gym and you really want to blame “growing pains” or a minor strain… just pause and consider that those hoofbeats you hear are actually those of the stampeding Osteosarcoma Zebra.



Haddox CL1, Han G2, Anijar L1, Binitie O3, Letson GD4, Bui MM5, Reed DR3. Osteosarcoma in pediatric patients and young adults: a single institution retrospective review of presentation, therapy, and outcome. Sarcoma. 2014;2014:402509. PMID: 24976784. [PubMed] [Read by QxMD]

Vijayakumar V1, Lowery R1, Zhang X1, Hicks C1, Rezeanu L1, Barr J1, Giles H1, Vijayakumar S1, Megason G1. Pediatric osteosarcoma: a single institution’s experience. South Med J. 2014 Nov;107(11):671-5. PMID: 25365431. [PubMed] [Read by QxMD]

Botter SM1, Neri D2, Fuchs B3. Recent advances in osteosarcoma. Curr Opin Pharmacol. 2014 Jun;16:15-23. PMID: 24632219. [PubMed] [Read by QxMD]

Lee RK1, Chu WC, Leung JH, Cheng FW, Li CK. Pathological fracture as the presenting feature in pediatric osteosarcoma. Pediatr Blood Cancer. 2013 Jul;60(7):1118-21. PMID: 23281226. [PubMed] [Read by QxMD]

Kim HJ1, McLawhorn AS, Goldstein MJ, Boland PJ. Malignant osseous tumors of the pediatric spine. J Am Acad Orthop Surg. 2012 Oct;20(10):646-56. PMID: 23027694. [PubMed] [Read by QxMD]

Gorlick R1, Khanna C. Osteosarcoma. J Bone Miner Res. 2010 Apr;25(4):683-91. PMID: 20205169. [PubMed] [Read by QxMD]


Sean M. Fox
Sean M. Fox
Articles: 583

One comment

  1. One thing I have never seen documented anywhere about osteosarcoma of the spine is that the pain is not necessarily at the site of the cancer. My son had osteosarcoma that started around the T4 area; he battled 6 years while the cancer spread. But never once did he complain of pain at the actual site of the cancer in his spine, except just after operations in that area. The pain was always in his side ribs. He did feel pain at the actual site for cancer in his legs, pelvis, etc. The doctors said it was referred pain; but I still find it difficult to understand how even when the cancer spread along his spine, he could not feel it there.

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