Question
A 12-year-old male presents to his provider with a 2-month history of pain in his lower right thigh. He describes the pain as “achy” in character, moderate in severity, and persistent in duration. On physical examination, there is a palpable mass in the distal right thigh. He adds that it is tender. He also exhibits a limited range of motion at the knee. Radiographs of the lower extremity reveal an osseous lesion with a radiodense matrix and a “sunburst” appearance. Local soft tissue extension is apparent. Which organ is the most common site of spread of the most likely lesion in this patient with inadequate treatment?
| A. |
Liver
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| B. |
Brain
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| C. |
Lungs
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| D. |
Adrenal glands
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Show Answer
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Correct Answer � C
Explanation
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Answer C) Lungs
Osteosarcoma is a lethal pediatric malignancy which most commonly occurs in the long bones of the lower extremity. Physical exam findings may include warmth and tenderness in the affected area, a palpable mass, and a limited range of motion when a joint is involved.
The lungs are the most common site of extraosseous metastasis. CT imaging of the chest may reveal pulmonary nodules with density (measured in Hounsfield units) similar to that of bone due to the production of osteoid by the metastatic osteosarcoma cancer cells.
The characteristic “sunburst” appearance of osteosarcoma seen on radiography is the result of aggressive periostitis.
Extrapulmonary metastasis related to osteosarcoma is exceedingly rare.
Approximately 15% of patients with osteosarcoma have detectable pulmonary metastases at the time of diagnosis. As a group, these patients continue to have a poor prognosis, with less than 20% long-term survival.
(Patients with one or a few resectable pulmonary metastases at presentation may have greater than 50% long-term survival, whereas patients with many, large, or unresectable pulmonary metastases have an extremely poor prognosis.)
Patients with non pulmonary metastases (e.g., bone metastases) have an even worse prognosis, with less than 5% long term survival. Patients with “skip” metastases (i.e., a metastasis within the same bone as the primary tumor or across the joint from the primary tumor) have the same poor prognosis as patients with distant metastases.
