The radiological appearance of giant cell tumors (GCT) in the developing skeleton was retrospectively assessed in 49 (10.6%) of the 462 patients with GCTs seen in consultation by the Netherlands Committee on Bone Tumors. There were 31 female and 18 male patients, all below 19 years of age. Thirty-four tumors were located in short and long tubular bones, two in the tarsus, while the others were in the pelvis, vertebral spine, and a rib. Involvement of the epiphysis in tubular bones was closely related to the age of the patient: the average age of the 3 patients with a lesion in the metaphysis was 11 years, that in the 6 patients with metadiaphyseal lesions 13 years, average age in the 10 patients with epimetaphyseal lesions 17 years, and it was also 17 years in the 17 patients with epimetadiaphyseal lesions. In tubular bones with the epiphyseal growth plates still open, the epiphysis was never involved, with the exception of two epimetadiaphyseal lesions in which closure of the growth plate was difficult to establish. Assessing GCT characteristics in this study population demonstrated that epiphyseal involvement increased with age and showed; to some extent, a predominance of female patients.

Primary synovial chondromatosis is a relatively uncommon condition. Synovial chondrosarcoma is considered to be very rare and it is not always clear whether the sarcoma develops by malignant transformation of synovial chondromatosis or whether it arises de novo. Differentiation of the two conditions on clinical and radiographic features is not possible and on histological criteria can be difficult. We report the case of a 59-year-old man who, 4 years after a synovectomy for synovial chondromatosis, developed a synovial chondrosarcoma of the hip. The literature is reviewed.

Tibial bone tunnels were examined with bone scans 2 years after patella ligament ACL reconstruction in 68 patients. At 2 years, scan uptake at the tibial tunnel was increased in 29% of patients. Marked increase of scintigraphic uptake was associated with tibial tunnel enlargement of more than 35% and a graft length in the tibial tunnel over 14 mm. Scan uptake was correlated to tunnel enlargement (r = 0.64, P < 0.01) and tunnel enlargement was correlated to graft length inside the tibial tunnel (r = 0.59 P < 0.001). No correlation was found between scan uptake or tunnel enlargement and anterior laxity, sagittal tunnel position and subjective outcome. Scintigraphy indicates the enlarged tibial tunnels are filled with remodelling bone. Tibial fixation location influences ligament healing inside the tunnel: Return of osseous homeostasis at the tibial tunnel can take more than 2 years when fixation is more than 14 mm below the joint.

Desmoplastic fibroma is a rare benign primary bone tumor, histologically identical to the extra-abdominal desmoid tumor of soft tissues. The incidence in major series of bone tumors is 0.1%-0.3%. In the present study 18 cases from the files of the Netherlands Committee on Bone Tumors are reported, with an emphasis on the radiographic features. Eight female and ten male subjects were affected, with a fairly even age distribution from the second to the seventh decade of life. The most frequent sites of involvement were the femur and the pelvis. Radiographically the lesions nearly always demonstrated benign features with respect to pattern of destruction, margins, and reactive bone formation; however, soft tissue extension was sometimes present. Although desmoplastic fibroma usually presents with pain or swelling, in 5 of the 18 cases the existence of the lesion was an accidental finding, and in 2 cases the patient had long-standing, vague complaints of pain. Though overall benign radiographic features may support the final diagnosis, the main and often troublesome histological differential diagnosis is of a low-grade fibrosoma. En bloc resection is the treatment of choice in view of the high incidence of recurrence after curettage.

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