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 Erich Fogg, PA-C, MMSc, DEPARTMENT EDITOR Lisa DiSandro, MS, PA-CThe author works in orthopedic oncology at M.D. Anderson Cancer Center, Houston, Tex. She has indicated no relationships to disclose relating to the content of this article. Erich Fogg is Assistant Professor in and Program Director of the Physician Assistant Program at the College of Health Professions, University of New England, Portland, Me.CASEThe patient is a 38-year-old woman who complained of having pain in her right knee over the past 6 months. She reported no history of injury or trauma. Her primary care physician treated her initially with analgesics, but her symptoms persisted. She was referred to an orthopedic surgeon who ordered plain films and MRI, both of which showed a lesion in the right proximal tibia.
History The patient described the pain as sharp in nature and localized to the anterolateral aspect of the right knee. It radiated down the calf and worsened with activity. NSAIDs provided no relief. The patient could walk, but only for short distances. She reported that the pain was most pronounced at night after she had been on her feet all day. She was otherwise healthy with no other medical conditions. Physical examination Mild knee effusion was noted, along with diffuse soft tissue swelling along the medial thigh. There was increased warmth and bony tenderness over the lateral aspect of the right proximal tibia. The patient had full active and passive range of motion, without discomfort. The examination revealed no varus or valgus laxity, and tracking of the patella was normal. WHAT IS YOUR DIAGNOSIS?
DISCUSSIONFine needle aspiration core biopsy was performed and confirmed a diagnosis of giant cell tumor. The plain films showed an eccentric lytic lesion in the epiphysis of the bone, affecting the lateral tibial plateau, with expansion of the lateral cortex. MRI supported the diagnosis by showing that the lesion extended to subchondral bone. Both of these findings are classic for giant cell tumors. Treatment The patient was taken to the operating room for definitive treatment. Surgical intervention consisted of aggressive curettage with a high speed burr. Reconstruction of the cavitary defect was performed with polymethylmethacrylate cementation. Comment Giant cell tumors make up 15% of all symptomatic benign bone tumors and are the most common type. They occur most often in persons older than 30 years, but a few arise in skeletally immature patients. Approximately twice as many women as men are affected. The most common symptoms and signs include pain and localized swelling. Some patients may even present with a pathologic fracture. The classic location is in the epiphysis of long bones, with 50% of all lesions affecting the distal femur and proximal tibia; they can also arise in the distal radius, proximal humerus, vertebrae, and sacrum. The tumor itself usually manifests as a lytic, expansile lesion with no matrix calcification. Appropriate testing includes plain films and MRI, but CT may also be useful to determine the effect on bone. The gross pathology of giant cell tumors is dark brown hemorrhagic tissue; microscopically, multinucleated giant cells and stroma cells are noted. Definitive treatment involves surgical excision and surveillance imaging. Chest radiography is important to rule out metastasis, which can occur in 1% to 5% of cases. With modern surgical techniques and aggressive burring, the recurrence rate is approximately 10%. When these lesions do recur, they usually do so within the first 2 years after treatment. |
The plain film demonstrated a well-defined lesion with a faint sclerotic border and a focal area of cortical breakthrough. No matrix calcification or periosteal reaction was identified (see Figure 1). MRI showed an eccentric lesion in the lateral tibial plateau with extension to subchondral bone. There was no intraarticular involvement, but edema was noted within the bone marrow. At that point, the patient was sent to our institution for further evaluation.