Approach to a suspected bone tumor (pediatrics): Clinical sciences

A bone tumor is a growth or lesion of bone that can be malignant or benign. It’s important to recognize a bone tumor early to provide prompt life- and limb-saving treatment.

History, physical exam, and imaging findings can be used to categorize bone tumors as high risk or low risk. High-risk bone tumors are likely to be aggressive and malignant and these include osteosarcoma, Ewing sarcoma, and aneurysmal bone cyst.

On the flip side, low-risk tumors are more likely to be benign and these include osteoid osteoma, osteochondroma, and non-ossifying fibroma, as well as simple bone cyst and Langerhans cell histiocytosis.

Okay, if your patient is presenting with chief concerns suggesting a bone tumor, your first step is to obtain a focused history and physical. Your patient will typically be between 10 and 20 years old and report symptoms like localized bone pain, swelling, or even a mass. Sometimes, your patient might have a history of a pathologic fracture.

On physical exam, you could notice a localized tenderness or a palpable mass, with or without a limited range of motion in the adjacent joint. With this spectrum of findings, you should consider a bone tumor, and order an X-ray.

Now here’s a clinical pearl to keep in mind! When evaluating a bone lesion on X-ray, you should consider its border, if it’s lytic or sclerotic, and the presence or absence of a periosteal reaction.

Borders can be well-defined, suggesting a slow, localized process, or poorly defined, suggesting a more rapid, destructive process. The bone lesion itself can either be described as lytic, meaning it is bone-destroying and appears radiolucent on X-ray; or sclerotic, meaning it is bone-producing and appears radiodense on X-ray.

Finally, the presence of a periosteal reaction, which refers to new bone production in the periosteum caused by irritation, suggests a more aggressive bone lesion. Periosteal reactions can range from mild, appearing as “onion skinning”, to a “sunburst” pattern, to the extreme break of the Codman triangle.

Okay, now that you’ve evaluated the X-ray, your next step is to assess for high-risk findings, which include the presence of a poorly defined border, a sclerotic lesion, or a periosteal reaction.

Let’s start with cases in which there are one or more high risk findings on X-ray. Any of these findings indicate that the bone lesion is likely to be aggressive or malignant, such as an osteosarcoma, Ewing sarcoma, or an aneurysmal bone cyst, so your next step is to order an MRI.

First, let’s discuss osteosarcoma. Affected individuals often have localized bone pain that is worse at night, as well as constitutional symptoms like fever, weight loss, and night sweats. They may also have a personal history of a genetic syndrome, such as Li-Fraumeni or retinoblastoma; or they may have had previous exposure to radiation.

On X-ray, osteosarcoma appears as a poorly defined, sclerotic lesion with a periosteal “sunburst” pattern. In severe cases, you might even detect a Codman triangle. Additionally, MRI typically reveals a bone mass, with or without an associated soft tissue mass. With these history and imaging findings, you should consider osteosarcoma, and obtain a bone biopsy.

If the bone biopsy reveals an osteoid matrix, the hallmark of this bone-forming tumor, you can confirm the diagnosis of osteosarcoma.

Before we move on, here’s a clinical pearl! Osteosarcoma is one of the most common primary malignancies of bone in children and adolescents. It’s distinguished from growing pains in that growing pains typically occur at night and are typically bilateral, whereas osteosarcoma has recurrent persistent pain, worse at night, and is typically unilateral.

On the other hand, a child with Ewing sarcoma will present with localized bone pain that is worse at night. Additionally, they might have systemic symptoms, such as fever, fatigue, or weight loss.

X-ray is notable for a poorly defined, lytic lesion with a periosteal “onion skinning” pattern. Just as with osteosarcomas, in especially aggressive cases of Ewing sarcoma, the X-ray may reveal a Codman triangle.