Anterior-posterior x-ray of the right hip of a 78-year-old man who has had persistent pain in this hip for 4 years
Coronal short tau inversion recovery (STIR) sequence magnetic resonance imaging (MRI) of the patient’s hip taken 2 years earlier
Anterior-posterior x-ray of the patient’s right hip taken 4 years earlier
A man, aged 78 years, presents with approximately 4 years of persistent pain in his right hip, with no known injury. Initial x-ray images of the hip were taken shortly after the pain started. The x-ray showed a benign-appearing lesion at the base of the femoral neck but was otherwise normal. The patient was advised to rest and use nonsteroidal anti-inflammatory drugs as needed.
Magnetic resonance imaging of the hip was ordered 2 years earlier during orthopedic follow-up for persistent pain and showed trochanteric bursitis and a lobular 3-cm lesion at the base of the femoral neck. The lesion appeared benign and was diagnosed as a likely enchondroma. A steroid injection was administered for trochanteric bursitis but provided only short-term relief. The patient then saw a spine surgeon who thought the pain was related to spinal stenosis. He received foraminal injections to the lumbar spine, but they failed to relieve his hip and thigh pain.
The pain is now becoming intolerable with weight bearing, and he is noticing increased pain at night. A second anterior-posterior x-ray of the hip appears to be unchanged from the one taken initially.
This case has been brought to you in partnership with the Journal of Orthopedics for Physician Assistants.
Submit your diagnosis to see full explanation.
It can often be difficult to determine whether a bone lesion is benign or malignant. As in this case, differentiating between a benign enchondroma and a malignant slow-growing chondrosarcoma is the critical challenge. In addition, treatment is vastly different between the two, as enchondromas can be observed and chondrosarcomas require surgery. Identifying distinct clinical and radiographic features of bone lesions is essential in determining the treatment plan.
Determining from where the patient’s pain is coming is the initial and most important step in ruling out malignancy. Despite several treatments, this patient continued to complain of hip pain, including pain at night (a hallmark sign of malignancy). Repeat imaging can determine whether the tumor has changed over time, which would be a sign of malignant transformation.
Enchondromas are benign cartilaginous tumors that do not change in size and appearance over time. The patient’s second set of x-rays showed no cortical breakthrough, soft tissue mass, or periosteal reaction that would indicate the lesion was malignant. In this case, a second magnetic resonance imaging (MRI) scan would have the most value to compare with the MRI 2 years earlier. Any subtle changes in the appearance of the lesion not appreciated on x-ray may be seen on MRI. Bone scans are less sensitive in the diagnostic workup of bone lesions because they may show increased uptake for both benign and malignant lesions.
MRI findings suggestive of chondrosarcoma include endosteal scalloping involving two-thirds of the cortices depth, broken cortices, periosteal reaction, and presence of a soft tissue mass. Clinical findings that suggest malignancy in this patient were worsening weight-bearing pain and night pain. The patient’s pain failed to respond to other treatments as well, suggesting the source of the pain was yet to be identified.
The patient later sustained a pathologic fracture through the right femoral neck. Computed tomography scan with contrast of the chest, abdomen, and pelvis performed for metastatic workup showed only the isolated lesion at the femoral neck. Bone scan confirmed an isolated lesion at the right hip, and protein electrophoresis was negative. Intraoperative biopsies taken during hip fracture surgery showed low-grade chondrosarcoma. The patient underwent proximal femoral replacement with wide resection.
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).
- Jackson DW. Enchondromas vs chondrosarcomas: tips for the orthopedic clinician. Orthopedics Today. December 2005. http://www.healio.com/orthopedics/oncology/news/print/orthopedics-today/%7B5177f19c-5ef4-4f6d-a0c0-205e592b527b%7D/enchondromas-vs-chondrosarcomas-tips-for-the-orthopedic-clinician. Accessed December 22, 2015.
- Stanislavsky A, Gaillard F. Enchondroma vs low-grade chondrosarcoma. Radiopaedia.org. http://radiopaedia.org/articles/enchondroma-vs-low-grade-chondrosarcoma-2. Accessed December 22, 2015.