Figure 1. Anteroposterior radiograph of the right leg.
Figure 2. Lateral radiograph of the right knee.
Figure 3. Magnetic resonance imaging of the tibial metadiaphysis.
A 36-year-old woman presents to the office with right knee and lower leg pain that has persisted for 1 year. She believes the pain may have started after a fall while hiking. She has had intermittent swelling and pain for a year, but the pain seems to have increased over the last month. Over the past several days she reports fever and chills, as well. The patient undergoes anteroposterior radiograph of her right leg (Figure 1) and lateral radiograph of her right knee (Figure 2). Magnetic resonance imaging (MRI) shows signal changes in the tibial metadiaphysis extending down to the proximal third of the tibia (Figure 3).
What is the best treatment option for this patient?
Submit your diagnosis to see full explanation.
The patient presented with a fever and MRI imaging consistent with osteomyelitis vs a tumor-like lesion in the proximal tibia. Although her fever and imaging suggested osteomyelitis, an aggressive bone cancer could not be ruled out. The most appropriate initial step in treatment is to obtain a bone biopsy to establish a definitive diagnosis.
The patient was admitted for a bone biopsy, which yielded pus-like material in the proximal tibia. Initial culture results showed no evidence of infection, and postoperative pathology results showed a final diagnosis of Ewing sarcoma. Ewing sarcoma is a malignant bone tumor that primarily affects patients between the ages of 5 and 25 years. Ewing sarcoma may closely resemble osteomyelitis on radiograph and MRI, which may result in difficulty differentiating the 2 diseases.1 Patients with Ewing sarcoma may present with pain and fever, which also confuses the clinical picture.
When bone cancer cannot be ruled out, an open bone biopsy should be performed. An open bone biopsy offers improved diagnostic accuracy over a percutaneous biopsy. Aggressive debridement of osteomyelitis can be performed as a second procedure if the biopsy confirms osteomyelitis. Treatment of Ewing sarcoma includes chemotherapy and radiation. Complete tumor resection is preferred when the tumor occurs in expandable bones.2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- McCarville MB, Chen JY,Coleman JL, et al. Distinguishing osteomyelitis from Ewing sarcoma on radiography and MRI. AJR Am J Roentgenol. 2015;205(3):640-651.
- Gibbs CP Jr, Weber K, Scarborough MT. Malignant bone tumors. JBJS. 2001;83(11):1728-1745.