Clinical characteristics and prognoses of six patients with multicentric giant cell tumor of the bone

Multicentric giant cell tumor of the bone (MGCT) is a rare entity whose radiographic, pathological and biological features remain confusing. We retrospectively reviewed six patients (1 male, 5 female; average age, 22.33 years) treated for confirmed MGCT between 2001 and 2015. The patients' clinical information, images from radiographs (n = 14), CT (n = 13), MRI (n = 8), bone scintigraphy (n = 1) and PET-CT (n = 2), as well as histologic features, treatment and prognosis were analyzed. A total of 17 lesions were detected: 4 around the knee joint, 3 in the greater trochanter and head of the femur, 5 in the small bones of the feet, and 2 in flat bones. All these lesions occurred in an ipsilateral extremity. One patient had Paget's disease. On radiographs and CT, 12 lesions exhibited sclerotic margins or patchy sclerosis, 8 showed cortical discontinuity, and 5 showed soft tissue masses. On histopathology, 8 lesions showed signs of sarcomatous transformation and one had transformed into osteosarcoma. Ten lesions in 4 patients were initially treated with surgery, and 3 showed local recurrence. Seven lesions in 3 patients were treated with denosumab. All the patients are currently stable without metastasis. These results suggest MGCT tends to occur in uncommon sites with sclerosis. Because these lesions can be aggressive, patients should be carefully monitored for the recurrence or formation of other lesions, especially in an ipsilateral extremity.