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

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Introduction0:00–0:45

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.

History & Physical0:45–2:34

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.

High Risk Findings Present2:34–2:59

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.

Osteosarcoma2:59–4:20

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.

Ewing sarcoma4:20–5:26

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. MRI typically reveals a bone mass, with or without an associated soft tissue mass.
With this collection of findings, you should consider Ewing sarcoma, and proceed with a bone biopsy. If the biopsy reveals small round blue cells, you can confirm the diagnosis of Ewing sarcoma.Here’s a high yield fact!
Osteosarcoma and Ewing sarcoma can be distinguished not only by the history and imaging findings, but also from the tumor location.
While osteosarcoma usually involves the metaphysis, Ewing sarcoma is more likely to involve the diaphysis of the long bones.
Finally, let’s consider a child with an aneurysmal bone cyst, who will typically report localized bone pain and swelling.

Aneurysmal bone cyst5:26–6:10

Their history might also reveal a previous pathologic fracture. X-ray findings will typically show an expansile, lytic lesion with a “soap bubble” appearance; while MRI will show bone septae with cysts containing multiple fluid lines.
These imaging findings should make you consider an aneurysmal bone cyst, which is a non-malignant but highly aggressive, destructive, blood-filled vascular lesion of the bone.
Your next step is to perform a bone biopsy, and if the aspirate is bloody, then you can confirm the diagnosis of aneurysmal bone cyst.Now, let’s go back to our initial X-ray and discuss patients who did not have high risk X-ray findings.

No High Risk Findings6:10–6:41

In this case, your patient is more likely to have a benign bone lesion, such as an osteoid osteoma, osteochondroma, fibroma, or simple bone cyst; but may still have aggressive lesions, such as those that occur with Langerhans Cell Histiocytosis.Let’s start by discussing osteoid osteoma, which is a benign bone-forming lesion.

Osteoid osteoma6:41–7:06

Affected patients present with localized bone pain that is worse at night and relieved by NSAIDs. X-ray findings include a well-defined lesion with central lucency, called the nidus, that’s surrounded by sclerotic borders.
With these history and imaging findings, you can diagnose osteoid osteoma. On the other hand, a child with osteochondroma is likely to be asymptomatic or have only mild pain.

Osteochondroma7:06–7:33

Often, osteochondromas are found incidentally on imaging, and, on X-ray, they appear as a well-defined, cartilage-capped bone spur.
In some individuals, you might notice multiple lesions. With these imaging findings, you can diagnose osteochondroma, which is a cartilage-forming lesion.Next, let’s discuss a non-ossifying fibroma, or NOF for short, which is a fibrous lesion that forms when a bone fails to ossify, often in an area with a developmental defect.

Non-ossifying Fibroma7:33–8:00

NOFs are usually first detected as an incidental finding on X-ray, and appear as well-defined, lytic lesions with sclerotic borders, and there may be multiple lesions present.
With these imaging findings, you can diagnose fibroma. Next up is a simple bone cyst!

Simple bone cyst8:00–8:21

A child with a simple bone cyst may present with a pathologic fracture, and their X-ray will demonstrate a well-defined, cystic lesion.
Unlike aneurysmal bone cysts, simple bone cysts don’t have a vascular component, they aren’t as aggressive or destructive, and they tend to resolve spontaneously with skeletal maturity.Finally, a child with Langerhans cell histiocytosis, or LCH for short, may present with localized bone pain with a raised, soft, tender spot.

Langerhans cell histiocytosis8:21–9:47

In some cases, you may also notice an eczematous rash. On X-ray, LCH bone lesions appear well-defined and lytic, with a “punched-out” appearance.
LCH lesions can occur in any bone, but common sites include the skull, ribs, spine, and long bones. Finally, in some patients you might notice multiple lesions.Now, one last high-yield fact!
Langerhans cell histiocytosis is a proliferative disorder in which mutated Langerhans cells, a specific type of immune cell, proliferate in different parts of the body.
Langerhans cells can be found in the lymph nodes, lungs, liver, spleen, skin, and bone marrow, and symptoms vary, depending on which organ is affected.
In fact, LCH can be localized and present with isolated lesions in the bone or skin; or systemic, affecting multiple body systems.
Examples of LCH multisystem disease include CNS involvement, like pituitary gland dysfunction leading to diabetes insipidus, infertility, or hypothyroidism; gastrointestinal involvement like hepatosplenomegaly; and bone marrow involvement, resulting in pathologic fractures and pancytopenia.

Review9:47–10:47

Alright, as a quick recap… A bone tumor is a growth or lesion of the bone and often presents with localized bone pain or a palpable mass.
When you suspect a bone tumor, your first step is to order an X-ray, if a bone lesion is identified, you should assess for high-risk findings.
These include a poorly defined border, lytic or sclerotic lesion, or periosteal reaction. If high-risk findings are present, then the lesion is likely aggressive or malignant, and you should order an MRI.
Next, you can use history, imaging findings, and bone biopsy results to differentiate between osteosarcoma, Ewing sarcoma, and aneurysmal bone cyst.
On the other hand, if there are no high-risk findings, then the lesion is less likely to be malignant. Again you can use history and imaging findings to differentiate between osteoid osteoma, osteochondroma, non-ossifying fibroma, simple bone cyst, and Langerhans cell histiocytosis.