What are the Common Benign Bone Tumors?

Patient Presentation
A 4-year-old female was sent to the emergency room of a regional children’s hospital for treatment of a right femur fracture.
The child had been playing outside with her older siblings and tripped over a sandbox while playing and hit her knee. She was able to get up and come into the house where she again fell in the doorway.
She refused to walk and was taken to a local emergency room. Radiographs were obtained and showed a non-displaced femur fracture located a bone lucency.
Because of the lucency she was sent to the children’s hospital for further evaluation and management.

The past medical history showed a healthy child with a normal diet. The family history showed heart disease and diabetes and no bone problems or cancer in the family. The review of systems was negative including weight loss, sweating, problems bruising or bleeding.

The pertinent physical exam showed a healthy 4 year old with normal growth.
Skin examination showed minor shin bruising. She had some mild redness over her right patella and complained of pain just above the knee with palpation and movement. Hip and ankle examination were normal as was the rest of her examination.

The radiologic evaluation showed an oblique non-displaced distal femur fracture through a radiolucent lesion with a well-defined border with no periosteal reaction. There was no soft tissue swelling. The diagnosis of non-ossifying fibroma with a pathological fracture of the femur was made.

The patient’s clinical course including consulting orthopaedics who placed her into a hip spica cast as a long leg cast would not be long enough to approximate and fix both fracture ends.
She was admitted to the hospital for cast placement and parental education about the cast. She was to followup in the orthopaedic clinic in 2 weeks.

Figure 77 – AP and lateral radiographs of the right knee demonstrate an acute, non-displaced oblique pathologic fracture through the distal right femur that occurs in an underlying radiolucent lesion that is well marginated and most consistent in appearance with a non-ossifying fibroma.

Discussion
Fibrous cortical defect or non-ossifying fibroma (also called fibroxanthoma) is a common benign bony tumor. If < 4 cm and close to the cortex they are called fibrous cortical defects. If larger and if they enter into the intramedullary canal they are called non-ossifying fibromas. Up to 30% of children with open growth plates may have one.
Radiographs show ovoid, scalloped lucencies in the metaphyseal cortex of a long bone with a sharply marginated surrounding rim of reactive bone, with no associated soft tissue mass.
These tumors usually spontaneously resolve and usually no treatment for them is necessary.

Learning Point
Other Common benign bone tumors include:

• Osteochondroma – Most common benign bone tumor in children. They are outgrowths of normal bone and cartilage that occur in abnormal locations usually in the metaphysis of long bones. Radiographs show normal tracecular bone and bone density with no reactive bony changes. Lesions can be pedunculated or sessile.
  Treatment is usually monitoring.

• Bone cysts
  • Simple or unicameral – a cystic lesion located at the ends of long bones usually near the physis. Radiographically there is a lucency sometime with ridges of cortical bone. As they may have associated pathological fractures, treatment of the fracture is needed along with aspiration. Treatment with bone grafting also may be indicated.
  • Aneurysmal bone cysts – occur uncommonly in children usually in the long bones but also in the spine. They may occur in the metaphysis or diaphysis. Treatment is curretage and bone grafting.
• Enchondroma – a cartilage tumor found in the hands and feet often in the diaphyseal or metaphyseal areas. They may be singular or multiple. Radiographs show a radiolucent lesion with thin cortex and little or no reactive bone. Sometimes there is speckled calcification within the lesion.
  Rarely has malignant transformation. Treatment is curretage and bone grafting.

• Osteoid osteoma – painful lesions occurring often in the tibia and femur. Radiographs show a radiolucent nidus with surrounding dense reactive bone. Natural history is one of resolution but they are so painful that surgery may be necessary for relief.
• Osteoblastoma – is similar to osteoid osteoma but occurs often in the spine, feet or ribs. These are also larger (> 1.3 cm in size). Some malignant variants have been reported.

Eosinophilic granulomas can be considered benign as they act benign but they are part of a system disease process that often needs treatment.
Chondroblastomas can also be considered benign but they often metastasize to other areas and it is not certain if they actually spontaneously resolve, therefore they are usually treated if found by resection, or other treatment.

Questions for Further Discussion
1. What are common malignant bone tumors and what is their radiographic appearance?
2. What are the indications for further radiological evaluation of a bone lesion?

Related Cases

Disease:
Non-ossifying Fibroma of the Bone | Bone Diseases | Fractures

Symptom/Presentation:
Lower Extremity Trauma

Specialty:
Emergency Medicine | Orthopaedic Surgery and Sports Medicine |Radiology / Nuclear Medicine / Radiation Oncology

Age:
Preschooler

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Benign Tumors and Bone Diseases.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Jee H, Choe BY, Kang HS, et. al. Nonossifying fibroma: characteristics at MR imaging with pathologic correlation. Radiology, 1998;209:197-202.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:2451-2455.

Smith SE. Fibrous Cortical Defect and Nonossifying Fibroma. eMedicine. Available from the Internet at http://emedicine.medscape.com/article/389590-overview (rev. 11/27/2007, cited 4/27/2009).

ACGME Competencies Highlighted by Case