What is the diagnosis?

Monostotic fibrous dysplasia of the femur 

• Pearl: Fibrous dysplasia is a developmental abnormality caused by a GS alpha protein mutation that leads to failure of the production of normal lamellar bone, and instead with ensuing abnormal proliferation of fibrous tissue [1].

Image 2. Femoral plain film, same as above with annotations by editor. Circle indicates lucency commonly seen with fibrous dysplasia, arrows indicate endosteal scalloping, and square represents bony sclerosis. All findings consistent with fibrous dysplasia. Original image courtesy of Frank Gaillard, Radiopaedia.org. rID: 16465

What is the mechanism of injury?

The monostotic form of fibrous dysplasia, accounting for 75-80% of cases, often presents as a pathologic fracture, with or without minor inciting trauma [1]. 

What physical exam findings are expected?

On examination, fibrous dysplasia may present with visual deformities of the involved sites (often the ribs, long bones, and craniofacial structures). Focal palpation may also increase pain with fractures [1].

Which imaging modalities can be used?

Plain radiographs of the affected bone are sufficient to diagnose fibrous dysplasia. However, CT and MRI can exclude other bone lesions. For polyostotic cases, bone scans demonstrating increased Technetium-99m radiotracer uptake may be used to assess disease extent. Lastly, when concerned for lesions that may mimic malignancy, a bone biopsy would be necessary [1].

• Pearl: Diagnosis on imaging will show a lesion with ground glass appearance or a “punched out” lesion with a well-defined margin of sclerotic bone.

What is the management in the ED?

In asymptomatic cases, treatment is nonoperative, with bisphosphonates for pain control. 

When do you consult Orthopedics?

Orthopedics should be consulted for pathologic fractures requiring internal fixation or correction of extremity and spine deformities and limb length discrepancies.

Cite This Article

Do M, Tomesch A. A Missed Connection. Ortho EM Pearls. March 2023.